Spec out delegate interface for milestone sync
Stub out ThingsSyncDelegate for milestone support
Add missing forward class declaration to ThingsHubConfiguration
Add sync begin callback to issue sync delegate
Make error domain constants mirror app return codes
Add some methods to NSDictionary+GithubAPIAdditions
Implement sync algorithm in sync engine
Implement milestone sync & supporting methods in ThingsSyncDelegate
Merge pull request #3 from cdzombak/cdz/milestone-sync

Add milestone sync