Bug 1041124 - [Messages][Refactoring] Make use of EventDispatcher in MessageManager. r=julien

> can't we set beforeEnter and afterLeave in "report"? I think "group" does not need it, right?
You can keep onDeliverySuccess and onReadSuccess in "report", and do the binding once in beforeEnter ? Or add a "constructor" function in "report" that would be called in Information.

Yeah, good point. I probably need ```init``` function in report view to call bind on ```onDeliverySuccess\onReadSuccess``` (constructor will require more unrelated to this patch changes).

> (looks more and more like we'd need a real prototype-based inheritance here :) ).

IMO the majority of the code in this file belongs to report view, so one more option would be to just divide these two panels into two files and move ```renderContactList``` to shared_components.js for example.