Removing change methods to mixin in Data
Merge branch 'origin/separateDataChangeListeners' into feature/notification_mixin
Generalizing mixin to match Collection classes
Beautifying
Removing unused imports
Merge branch 'master' into feature/notification_mixin

Conflicts:
	lib/src/data_collection.dart
	test/id_generator_test.dart
isolated last parts of notification from data_collection
Merge pull request #17 from cleandart/feature/notification_mixin

Feature/notification mixin