Edit feature Category. if category deleted, Event will not have that category in it fields

Signed-off-by: Hui Zheng <fengyimzy@gmail.com>
Merge branch 'feature-Category&Filter' into dev-team3

Conflicts:
	Calendar/src/edu/wpi/cs/wpisuitetng/modules/calendar/model/EventEntityManager.java
	Calendar/test/ModelTest/CommitmentTests.java
	Calendar/test/ModelTest/EventTests.java
	Core/WPISuite/WebContent/WEB-INF/lib/WPISuite-Interfaces.jar