Implemented reset for group password.
Also changed the get suggestion button to disabled instead of invisible when no suggestion has been made
Fix bug with activity stack growing to infinity if the user navigates only using groupHistoryActivity.
Merge branch 'groupSuggestion' of https://github.com/lca4/unison-android into groupSuggestion
correct application behavior for enabling/disabling the suggestion button
Merge branch 'groupSuggestion' into dev/solo

Conflicts:
	src/ch/epfl/unison/ui/GroupsActivity.java