Made it so new commitments can have their own categories, but changing
categories for old commitments is still buggy.
New commitments now support categories, and also fixed some bugs in
commitment creation/editing.
Merge branch 'dev' into commitment_categories

Conflicts:
	IncrediblyGorgeousCalendar/src/edu/wpi/cs/wpisuitetng/modules/cal/models/Commitment.java
	IncrediblyGorgeousCalendar/src/edu/wpi/cs/wpisuitetng/modules/cal/ui/AddCommitmentDisplay.java
READ FULL MESSAGE! Implemented de-selecting all events and filtering
commitments by category

Since commitments that were on the database before categories in
commitments were implemented do not contain a category, they create
trouble with this. As a result, please delete database before merging
this.

Will make UI of side bar panel prettier.
Finished implementation of commitment filtering by category.

Improved UI, created top level events and commitments filter which are
independent of category filter.
Refresh category filters upon addition/deletion in category manager
Merge branch 'dev' into commitment_filter

Conflicts:
	IncrediblyGorgeousCalendar/src/edu/wpi/cs/wpisuitetng/modules/cal/ui/AddCommitmentDisplay.java
Merge pull request #59 from cs3733-team4/commitment_filter

Commitment filter