Don't add resources from message stanzas. Fixes #632

For each user we keep a list of currently online resources. These resources
were taken from both presence and message stanzas.

Receiving a message doesn't however indicate that the user is online,
especially in the case of archived messages.

This also abused the semantics of messages, which are meant to indicate
user presence.

docs/CHANGES.md

 # Changelog
 
 ## 1.0.6 (Unreleased)
+- #632 Offline and Logout states do not properly update once users start
+  chatting. [chrisuehlinger, jcband]
 - #674 Polish translation updated to the current master. [ser]
 - Typing (i.e. chat state) notifications are now also sent out from MUC rooms. [jcbrand]
 - `ChatRoomView.onChatRoomMessageSubmitted` has been renamed to

src/converse-core.js

@@ -1376,7 +1376,6 @@
                     return true; // We already have this message stored.
                 }
                 chatbox.createMessage($message, $delay, message);
-                converse.roster.addResource(contact_jid, resource);
                 converse.emit('message', message);
                 return true;
             },