Moves conversation features from LocalService to a new ConversationFacade.
It will allow Presenters to only communicate with low level layers.

This commit fix a ConcurrentModificationException
Switch putAll() to put() on textMessages and historyCalls fix the crash
Refactor calls to HistoryService to be asynchronous

Change-Id: I33fba4db759ec66777c3b88573d5901ce2d3b56f
Tuleap: #1367