Adaptation of the interface with the Manager

Due to the way the clustering will work, the interface for communicating with
the TweetManager is changed.
See: https://github.com/TweetAggregator/TweetAggregator/wiki/Tweet-Manager.
Merge branch 'master' of https://github.com/TweetAggregator/TweetAggregator

Conflicts:
	app/models/CommunicationModels.scala