Implementation of group passwords
new layout files for group password dialogs
Fixed minor merging conflicts in strings.xml
Merged unisonMenu to accomodate home and password options
Merge master into groupSuggestion with password modif
Now delete remaining LoginActivity when starting the app after signup.
Added a menu for phones with a small screen that replaces the SignUp button.
Prompt for password in History.
Modified the behviour for group suggestions.
It is now only display once as long as it is not a new group being suggested.There is a button in GroupsActivity that can be used to easily access the suggestion again even if it was refused.
Clicking on the button will simply display the same pop-up as before without any new server communication. In particular it should be noted that the list of users in the group will NOT be updated.
Merge branch 'groupSuggestion' into dev/solo

Conflicts:
	src/ch/epfl/unison/api/UnisonAPI.java
	src/ch/epfl/unison/ui/GroupsActivity.java
	src/ch/epfl/unison/ui/GroupsHistoryActivity.java
	src/ch/epfl/unison/ui/MainActivity.java