title: Error while starting ejabberd with xml_rpc
body: <p>I try to configure xmlrpc in my ejabberd server but the server doesnt seem to start after configuring xmlrpc. My ejabberd config is :</p>
  
  <pre><code>{listen,[
  {{4560, "127.0.0.1"}, ejabberd_xmlrpc, [
      {access_commands, [
        %% This bot can only execute the command 'register',
        %% and if argument 'host' is provided, it must be "example.org":
        {xmlrpcaccess, [register], [{host, "myhost.com"}]}
      ]}
    ]},
  //many modules added here
  ]}.
  {acl, xmlrpcbot, {user, "USER", "myhost.com"}}.
  {access, xmlrpcaccess, [{allow, xmlrpcbot}]}.
  </code></pre>
  
  <p>and when I start service, I get the below log:</p>
  
  <pre><code>=INFO REPORT==== 2014-04-08 17:26:45 ===
  application: ejabberd
  exited: {bad_return,
           {{ejabberd_app,start,[normal,[]]},
            {'EXIT',
             {noproc,
              {gen_server,call,
               [ejabberd_sup,
                {start_child,
                 {ejabberd_odbc_sup_localhost,
                  {ejabberd_odbc_sup,start_link,["localhost"]},
                  transient,infinity,supervisor,
                  [ejabberd_odbc_sup]}},
                infinity]}}}}}
  type: temporary
  </code></pre>
  
  <p>Of course the service runs if I comment all xml_rpc config lines. What's causing the error? Thanks</p>