Added a convenience method for getting uuid from RemoteModels
Record task outstanding entries when tag added or removed
Suppress outstanding entries when creating new tag links during sync
Fixed issues with writing tag_added or tag_removed to json in ChangesHappened
Refactored some client to server logic so that ChangesHappened doesn't have to do a bunch of expensive stuff on instantiation
Fixed to pushed_at unit test (still has time zone issues)
Added equality checking to ChangesHappened
Don't try to sync an empty payload
Fixed bug/ANR when adding tags
Refactor to prevent database locks
Don't create unecessary changeshappened messages