[java] Code refactored to simplify the verification process

Conflicts:
	src/selectvoting/system/core/Utils.java
	[java] Refactoring to mirror the code which is formally verified

Conflicts:
	src/selectvoting/system/core/CollectingServer.java
	src/selectvoting/system/core/Utils.java
	[java] CollectingServer: variable name 'ballots' changed to 'innerBallots'