Huge Update (Material Design, Added Maps etc.)

- Updated to use AppCompat v21
- Moved updating of database to an AsyncTask
- Introduced Material Design
- Added Cart, Ordered Items (Unimplemented yet)
- Added dialog box listing what stall you have selected
- Added Google Maps API
- Added permissions required for Google Maps
- Added icon to checkout and view map location of a canteen
- Added debug key for Google Maps API
- Moved some text strings around
- Added action items in action bar on some activities
- Moved around some textviews in list stalls listview
- Upgraded all activities to extend ActionBarActivity (to allow
AppCompat v21 support)
- Removed unnecessary code
- Bug Fixes Galore :ghost: