add feature: user can remove self from shared fridge
all pre-existing tests passing
add #remove_user fridge controller test
add feature test: user can remov self from shared fridge that they do not own
add controller test to make sure remove_user doesn't remove fridge from db; all tests passing
Merge branch 'master' into user-can-remove-self-from-shared-fridge
Merge branch 'master' into user-can-remove-self-from-shared-fridge
resolve merge, all tests passing
Merge pull request #37 from gopher-snakes-2013/user-can-remove-self-from-shared-fridge

User can remove self from shared fridge without deleting fridge from db