Update spec_helper
Remove unnecessary error handling
Update spec_helper
Add a module that handles events thread-safely
Refactor notifications
Merge remote branch 'origin/master' into feature-interface-event
Reimplement Notifications#handle_event
Change spec description
Update spec
Add some event constants
Refactor managers to create items thread-safely
Remove unnecessary spec
Constantize event constants
Fix typo
Forgot to change event name
Refactor event handlers
Allow handle_event to call private method
Refactor create_item
Remove handle_event that unexpectedly overwride a superclass method
Remove lines no longer used