Refactoring + fix bug in Clustering Home made

Refactoring:
	1. New .scala file for models for the clustering
	2. New package for the clustering algorithm
	3. Refactoring of the Cluster model
Fix Bug:
	1. No more infinite loop in ClustHC
	2. No more loss of data in ClustHC
Merge branch 'master' of https://github.com/TweetAggregator/TweetAggregator

Conflicts:
	app/models/CommunicationModels.scala
	test/ClusteringTests.scala