title: Sending email with postal from heroku fires strange exception
body: <p>I am trying to send email from Pedestal application hosted on Heroku using Postal.
  Email should be send in POST /send_email handler.</p>
  
  <p>But it fails with:</p>
  
  <pre><code>clojure.lang.ExceptionInfo:
  Interceptor Exception: No implementation of method: :make-input-stream of   
  protocol: #'clojure.java.io/IOFactory found for class: nil
  </code></pre>
  
  <p>It works locally or via repl running on heroku.</p>
  
  <p>Source:</p>
  
  <pre><code>(ns team-happiness.routes
    (:require [io.pedestal.http :as bootstrap]
              [io.pedestal.http.route.definition :refer [defroutes]]
              [io.pedestal.http.body-params :as body-params]
              [postal.core :as postal]))
  
  (defn smtp []
    {:host (System/getenv "SENDGRID_HOST")
     :ssl true
     :user (System/getenv "SENDGRID_USERNAME")
     :pass (System/getenv "SENDGRID_PASSWORD")})
  
  (defn mail []
    {:from "bla@bla.com"
     :to "bla@bla.com"
     :subject "Hi!"
     :body "Hello from Heroku!"})
  
  (defn send-email [request]
    (postal/send-message (smtp) (mail))
    {:status 200 :headers {} :body ""})
  
  (defroutes routes
    [[
      [ "/send_email" {:post send-email}]
    ]])
  </code></pre>
  
  <p>Stack trace:</p>
  
  <pre><code>2015-08-26T21:22:25.474347+00:00 app[web.1]: clojure.lang.ExceptionInfo: Interceptor Exception: No implementation of method: :make-input-stream of protocol: #'clojure.java.io/IOFactory found for class: nil
  2015-08-26T21:22:25.474349+00:00 app[web.1]:    at clojure.core$ex_info.invoke(core.clj:4593) ~[na:na]
  2015-08-26T21:22:25.474350+00:00 app[web.1]:    at io.pedestal.impl.interceptor$throwable__GT_ex_info.invoke(interceptor.clj:31) ~[na:na]
  2015-08-26T21:22:25.474352+00:00 app[web.1]:    at io.pedestal.impl.interceptor$try_f.invoke(interceptor.clj:53) ~[na:na]
  2015-08-26T21:22:25.474354+00:00 app[web.1]:    at io.pedestal.impl.interceptor$enter_all_with_binding.invoke(interceptor.clj:141) ~[na:na]
  2015-08-26T21:22:25.474355+00:00 app[web.1]:    at io.pedestal.impl.interceptor$enter_all$fn__12957.invoke(interceptor.clj:156) ~[na:na]
  2015-08-26T21:22:25.474357+00:00 app[web.1]:    at clojure.lang.AFn.applyToHelper(AFn.java:152) ~[team-happiness-0.0.1.jar:na]
  2015-08-26T21:22:25.474358+00:00 app[web.1]:    at clojure.lang.AFn.applyTo(AFn.java:144) ~[team-happiness-0.0.1.jar:na]
  2015-08-26T21:22:25.474359+00:00 app[web.1]:    at clojure.core$apply.invoke(core.clj:630) ~[na:na]
  2015-08-26T21:22:25.474361+00:00 app[web.1]:    at clojure.core$with_bindings_STAR_.doInvoke(core.clj:1868) ~[na:na]
  2015-08-26T21:22:25.474362+00:00 app[web.1]:    at clojure.lang.RestFn.invoke(RestFn.java:425) ~[team-happiness-0.0.1.jar:na]
  2015-08-26T21:22:25.474364+00:00 app[web.1]:    at io.pedestal.impl.interceptor$enter_all.invoke(interceptor.clj:154) ~[na:na]
  2015-08-26T21:22:25.474365+00:00 app[web.1]:    at io.pedestal.impl.interceptor$execute.invoke(interceptor.clj:272) [na:na]
  2015-08-26T21:22:25.474367+00:00 app[web.1]:    at io.pedestal.http.impl.servlet_interceptor$interceptor_service_fn$fn__15523.invoke(servlet_interceptor.clj:398) [na:na]
  2015-08-26T21:22:25.474368+00:00 app[web.1]:    at io.pedestal.http.servlet.FnServlet.service(servlet.clj:28) [na:na]
  2015-08-26T21:22:25.474369+00:00 app[web.1]:    at org.eclipse.jetty.servlet.ServletHolder.handle(ServletHolder.java:751) [team-happiness-0.0.1.jar:na]
  2015-08-26T21:22:25.474371+00:00 app[web.1]:    at org.eclipse.jetty.servlet.ServletHandler.doHandle(ServletHandler.java:566) [team-happiness-0.0.1.jar:na]
  2015-08-26T21:22:25.474372+00:00 app[web.1]:    at org.eclipse.jetty.server.handler.ContextHandler.doHandle(ContextHandler.java:1111) [team-happiness-0.0.1.jar:na]
  2015-08-26T21:22:25.474373+00:00 app[web.1]:    at org.eclipse.jetty.servlet.ServletHandler.doScope(ServletHandler.java:498) [team-happiness-0.0.1.jar:na]
  2015-08-26T21:22:25.474375+00:00 app[web.1]:    at org.eclipse.jetty.server.handler.ContextHandler.doScope(ContextHandler.java:1045) [team-happiness-0.0.1.jar:na]
  2015-08-26T21:22:25.474376+00:00 app[web.1]:    at org.eclipse.jetty.server.handler.ScopedHandler.handle(ScopedHandler.java:141) [team-happiness-0.0.1.jar:na]
  2015-08-26T21:22:25.474377+00:00 app[web.1]:    at org.eclipse.jetty.server.handler.HandlerWrapper.handle(HandlerWrapper.java:98) [team-happiness-0.0.1.jar:na]
  2015-08-26T21:22:25.474379+00:00 app[web.1]:    at org.eclipse.jetty.server.Server.handle(Server.java:461) [team-happiness-0.0.1.jar:na]
  2015-08-26T21:22:25.474380+00:00 app[web.1]:    at org.eclipse.jetty.server.HttpChannel.handle(HttpChannel.java:284) [team-happiness-0.0.1.jar:na]
  2015-08-26T21:22:25.474381+00:00 app[web.1]:    at org.eclipse.jetty.server.HttpConnection.onFillable(HttpConnection.java:244) [team-happiness-0.0.1.jar:na]
  2015-08-26T21:22:25.474394+00:00 app[web.1]:    at org.eclipse.jetty.io.AbstractConnection$2.run(AbstractConnection.java:534) [team-happiness-0.0.1.jar:na]
  2015-08-26T21:22:25.474395+00:00 app[web.1]:    at org.eclipse.jetty.util.thread.QueuedThreadPool.runJob(QueuedThreadPool.java:607) [team-happiness-0.0.1.jar:na]
  2015-08-26T21:22:25.474397+00:00 app[web.1]:    at org.eclipse.jetty.util.thread.QueuedThreadPool$3.run(QueuedThreadPool.java:536) [team-happiness-0.0.1.jar:na]
  2015-08-26T21:22:25.474398+00:00 app[web.1]:    at java.lang.Thread.run(Thread.java:745) [na:1.7.0_79]
  2015-08-26T21:22:25.474400+00:00 app[web.1]: Caused by: java.lang.IllegalArgumentException: No implementation of method: :make-input-stream of protocol: #'clojure.java.io/IOFactory found for class: nil
  2015-08-26T21:22:25.474401+00:00 app[web.1]:    at clojure.core$_cache_protocol_fn.invoke(core_deftype.clj:554) ~[na:na]
  2015-08-26T21:22:25.474402+00:00 app[web.1]:    at clojure.java.io$eval3371$fn__3372$G__3360__3379.invoke(io.clj:69) ~[na:na]
  2015-08-26T21:22:25.474403+00:00 app[web.1]:    at clojure.java.io$input_stream.doInvoke(io.clj:136) ~[na:na]
  2015-08-26T21:22:25.474404+00:00 app[web.1]:    at clojure.lang.RestFn.invoke(RestFn.java:410) ~[team-happiness-0.0.1.jar:na]
  2015-08-26T21:22:25.474406+00:00 app[web.1]:    at postal.support$pom_version.invoke(support.clj:61) ~[na:na]
  2015-08-26T21:22:25.474407+00:00 app[web.1]:    at postal.support$user_agent.invoke(support.clj:67) ~[na:na]
  2015-08-26T21:22:25.474408+00:00 app[web.1]:    at postal.message$make_jmessage.invoke(message.clj:177) ~[na:na]
  2015-08-26T21:22:25.474410+00:00 app[web.1]:    at postal.smtp$smtp_send_STAR_$fn__17638.invoke(smtp.clj:34) ~[na:na]
  2015-08-26T21:22:25.474411+00:00 app[web.1]:    at clojure.core$map$fn__560.invoke(core.clj:2624) ~[na:na]
  2015-08-26T21:22:25.474412+00:00 app[web.1]:    at clojure.lang.LazySeq.sval(LazySeq.java:40) ~[team-happiness-0.0.1.jar:na]
  2015-08-26T21:22:25.474414+00:00 app[web.1]:    at clojure.lang.LazySeq.seq(LazySeq.java:49) ~[team-happiness-0.0.1.jar:na]
  2015-08-26T21:22:25.474419+00:00 app[web.1]:    at clojure.lang.RT.seq(RT.java:507) ~[team-happiness-0.0.1.jar:na]
  2015-08-26T21:22:25.474420+00:00 app[web.1]:    at clojure.core$seq__27.invoke(core.clj:137) ~[na:na]
  2015-08-26T21:22:25.474421+00:00 app[web.1]:    at postal.smtp$smtp_send_STAR_.invoke(smtp.clj:35) ~[na:na]
  2015-08-26T21:22:25.474423+00:00 app[web.1]:    at postal.smtp$smtp_send.doInvoke(smtp.clj:58) ~[na:na]
  2015-08-26T21:22:25.474424+00:00 app[web.1]:    at clojure.lang.RestFn.invoke(RestFn.java:423) ~[team-happiness-0.0.1.jar:na]
  2015-08-26T21:22:25.474425+00:00 app[web.1]:    at postal.core$send_message.invoke(core.clj:35) ~[na:na]
  2015-08-26T21:22:25.474427+00:00 app[web.1]:    at team_happiness.routes$send_email.invoke(routes.clj:31) ~[team-happiness-0.0.1.jar:na]
  2015-08-26T21:22:25.474428+00:00 app[web.1]:    at io.pedestal.interceptor$eval13068$fn__13069$fn__13070.invoke(interceptor.clj:38) ~[na:na]
  2015-08-26T21:22:25.474429+00:00 app[web.1]:    at io.pedestal.impl.interceptor$try_f.invoke(interceptor.clj:50) ~[na:na]
  2015-08-26T21:22:25.474431+00:00 app[web.1]:    ... 25 common frames omitted
  2015-08-26T21:22:25.474631+00:00 app[web.1]: INFO  i.p.http.impl.servlet-interceptor - {:line 266, :msg "sending error", :message "Internal server error: exception"}
  </code></pre>