commit before merge with marc's refactoring
Merge branch 'groupSuggestion' of https://github.com/lca4/unison-android into groupSuggestion

Conflicts:
	src/ch/epfl/unison/ui/GroupsActivity.java
	src/ch/epfl/unison/ui/GroupsHistoryActivity.java
IMPORTANT COMMIT
finish merge of groupSuggestion and master. Now we should no longer use the old activities.
added support for group deletion on the server. The groupHistoryActivity now handles these cases.
modified servercomm: createGroup() is now called getGroupListAfterCreateGroup() and the new createGroup() should now return only the newly created group.
FIX JSON handling from server

JSON for new playlist are now correctly fetched and deserialized.
Merge branch 'groupSuggestion' into dev/merge
Replaces some getters to class fields by field names