added entrance processor interface
EntranceProcessor added as a Processor sub-interface. Project compiles.
Working refactoring
Encapsulated event injection inside the EntrancePI. EntranceProcessor now has a single output stream, which is set during the building phase. Removed TopologyStarter.
Storm EPI refactoring compiles (testing needed)
Introduced hasNext in EntranceProcessor
Remove TopologyStarter from S4. Moved looping code to S4DoTask.onStart() [following same strategy as SimpleEngine]
Merge branch 'entranceprocessor' of github.com:gdfm/samoa into gdfm-entranceprocessor

Conflicts:
	samoa-api/src/main/java/com/yahoo/labs/samoa/streams/ClusteringSourceProcessor.java
Merge pull request #41 from gdfm/entranceprocessor

Entrance Processor