Gamification Engine:

- service implementation:

	- created the service getBadgeList (for the badgeCollection plugin) for getting the list of badges of a specific customized badgeCollection plugin (defined the cases for all the customized badgeCollection plugins created until now)
	- created the related test for the service implemented
	- added badge images for all the customized badgeCollection plugins created until now
	- created new model for badge and deprecated the previous one
	- created comparators to support gamificationPlugin and customized badgeCollection plugins
	- various refactorings