Added notification center

Added notification center
Added basic achievement functionality
Moved some functionality from main file into achievements service
Moved more functionality to achievements module
Add duration parameter to addNotification (will default to 5s if omitted).
Merge branch 'notifications'
Merge remote-tracking branch 'remotes/origin/achievements'

Conflicts:
	index.html
	js/SpaceClickyGame.js
Merged "notifications" and "achievements" branch
Added toast when achievement is unlocked