title: SpringXD module configurations not being picked up
body: <p>Using SpringXD mail sink and wanted to configure the mail server settings in a properties file in the module config directory. I created a <strong>mail.properties</strong> file in the <strong>config/modules/sink/mail</strong> directory and placed all my server properties in there. the property names were the same as they are if used inline with the stream definition:</p>
  
  <pre><code>host=smtp.example.com
  port=25
  username=username
  password=secret
  from=somedude@example.com
  </code></pre>
  
  <p>However these did not get picked up. i know this because when i put them inline into the stream then they worked.</p>
  
  <p>I did check for typos in my file and in my folder/file names and there are none. Is there some special trick to configure modules that come with SpringXD this way?</p>