Allow twitter out node to specify extra parameters

to close #119. Thanks @sacbhale

social/twitter/27-twitter.html

@@ -205,6 +205,8 @@
     <p>To send a Direct Message (DM) - use a payload like "D {username} {message}"</p>
     <p>If <b>msg.media</b> exists and is a Buffer object, this node will treat it
        as an image and attach it to the tweet.</p>
+    <p>If <b>msg.params</b> exists and is an object of name:value pairs,
+    this node will treat it as parameters for the update request.</p>
 </script>
 
 <script type="text/javascript">