Copied EventListModel into CommitmentListModel to ensure that all
changes made for events also apply to commitments. Also removed two
unused imports.
Added Get and Remove Controllers and Observers for commitments. Robyn
Added get and edit for commtiments and made commitment list model match.
Robyn and Craig
EditEvent and EditCommitment now update the EventListModel and
CommitmentListModel, respectively, with the updated event/commitment.
Merge pull request #62 from bigamckay/wip/backend-commitments

Wip/backend commitments