New "PushChat" sample app

- Fixed: user-defined app-level pushReceived was not being called on a received push
- Fixed: DeleteUser from UserList was accidentally calling AddUser
- Fixed: Add and Delete User from UserList callbacks would not set Result correctly
Bring up login controller instead of Main
Merge branch 'develop' of github.com:BuddyPlatform/Buddy-iOS-SDK into na_push_chat
Merge remote-tracking branch 'upstream/develop' into na_push_chat
Put this back the way it was for now. May fix later
Fix observer warnings/crashes
Merge pull request #84 from nickatbuddy/na_push_chat

New "PushChat" sample app