- Pass an option object to addRosterItem which can contains information about
  the object catched in the rosterHandler.
  In this case I am marking the last item available in the roster of the
  person for which this handler is triggered

Removed rendering of rosterview since I've added check to render only with passed item and the result is the same without the rendering

- Fixed function has inconsistent return points by always specifying
  returns instead of returning only on condition
- Set room-jid as data-room-jid attribute to validate html5
- Added missing semicolon

Set modifications of model attributes only if the item received from the rosterHandler has different options

Pass item to render method of RosterView instead of looping over each item on every render call, Inverted visibility logic for contact titles in order to avoid multiple show and hide

Moved assignment of template for RosterView out of the render method to avoid calling empty and readding items everytime the render method is called

This has fixed some IE8 errors while parsing the presence stanza

So that it doesn't depend on it's element already being in the DOM

Also added a new jasmine spec for this as well as jquery.tinysort to do the
sorting.

Also add flush method to converse.js (used in ClientStorage tests)

Can succesfully connect now, but still need to get rid of ajax calls to @@xmp-userinfo, and replace them with
VCards.

This is necessary because each open tab in the browser is its own resource.

TODO: Ideally we should differentiate between resources in the browser (using
converse.js) and other resources (i.e from a desktop client).

- This allows multiple open tabs (which is each its own resource) to be aware
when one tab sent a message.