Merge pull request #10 from abiligiri/master

Remove unnecessary bin and gen files
Added actionbar nav and items in group lists and group create
adding resource files
Change title and hint messages
Changed the title of ListGroupActivity to "Groups"
Changed the hint "Invitation Message" to "Message"
Set inputType to email
Revert to older layout
Show name of group as title for Messages activity
Sort groups by timestamp of last message