approvals: added controlled and model.  added method on chore_history for approval callback.
database migration: fixed a typo where foreign key for approvals was roommate_id instead of user_id, causing tests to fail
trying to push, had to fix merge conflict with schema version numbering
updated readme to reflect that we're using httparty
Merge branch 'development' of github.com:jasonleibowitz/SplitMate into development