title: Rails 4 and grape - undefined method `call' when splitting API file
body: <p>I've got a vanilla rails 4 application and I'm trying to add a versioned Grape API. The rails server starts up fine, but when I try to access the API URL (<code>http://localhost:3000/v1/user/ping</code>), I get the error:</p>
  
  <pre><code>undefined method `call' for V1:Module
  </code></pre>
  
  <p>So far, the API I have setup is very simple, but I can't figure out why it is not working</p>
  
  <p>root/app/api/api.rb:</p>
  
  <pre><code># root/app/api/api.rb
  class API &lt; Grape::API
    mount V1
  end
  </code></pre>
  
  <p>Within the version folder, I want to have all the classes that the version of the API supports: root/app/api/v1/user.rb:</p>
  
  <pre><code># root/app/api/v1/user.rb
  module V1
    class user &lt; Grape::API
      get :ping do
        { :ping =&gt; params[:pong] || 'pong' }
      end
    end
  end
  </code></pre>
  
  <p>root/config/routes:</p>
  
  <pre><code>TestApp::Application.routes.draw do
    mount API =&gt; '/'
  end
  </code></pre>