This time when a message is received for the first time.

More code optimizations

- Chain calls on initialize method of RosterView
- Moved dom insertion out of loops on initialize method of
  XMPPStatusView

Wrap this with jQuery only once in subscribeToSuggestedItems; Same thing with presence in presenceHandler

- removed extra jQuerify wrapping of message at onChatRoomMessage
- Construct an array of strings and add it to onChatRoomRoster only
  after loop is done in order to have only 1 dom insertion

- Chained call to render and show methods of ChatBoxView
- Cached target for subscribeToContact
- Removed check of length > 0

- Removed situation where extra data passed in keyPressed was overriden
  with the same result because of the two assignments inside the if
  statements
- Cached fullname and presence_type at initialize of ChatBoxView

- Cached length of every iteration in order to avoid having to calculate
  length on every iteration
- Changed insertClientStoredMessaged length check to use the simple length of
  the array instead of using underscore size since
- Added description with need of underscore size method for roster on
  onChatRoomRoster since the roster is an object not an array

- Added missing var statements for variable declarations
- Added TODO entries for code that needs to be used or further tested
- Removed unused variables
- Removed check of length > 0 as it's enought to check just item.length
  as a boolean
- Renamed scrolldown to scrollDown to keep a consitent style of method
  naming
- Removed extra jQuery wrapping for many objects and instead define it
  once and use it in the other places
- Use jQuery chaining for modifying connecting message in
  jarn.disconnect
- Define wrapped message in messageReceived from line 342 instead of
  expecting it to be received from the other messageReceived function

Optimize actions done in RosterView. 

Code clean up + updated error message

Added error_icon.png and spinner.gif images to not make it dependent of
Plone resources.

Check also if subscription === to in order to correctly move the accepted contact subscription from pending to current

Prevent default event for the removeContact link in order to avoid page reload when jQuery Dialog is openened from clicking on the delete link

Show dt elements on xmppchat-roster only if they have length and they are not already visible to avoid making them all the time visible when they might already be so

- Subscribe event with help of jQuery one instead of delegate, now that
  the rosterView is no longer emptied on every render to avoid
  registring several handlers of remove action, which meant you had to
  click 4 times for the jQuery Dialog to go away
- Remove the element from the rosterView when the remove event is
  triggered on the model which removes just that item instead of
  emptying the list and appending the remaining models again