Added device_type for User model
Created UserAnnoState model
Updating UserAnnoState after any action on anno by user
Added API to update notify of UserAnnoState
Added API to change notify state for an anno
Modified UpdateSchema for generating UserAnnoState model of existing annos
Made UpdateAnnoHandler secure
Merge branch 'feature/usb' into feature/push-notifications

Conflicts:
	anno_gec_server/app.yaml