Added a map layer button on map to allow users to select different map types.  Map type is saved in shared preferences.

fixes #3
ASAM offline map

- added natural earth land polygon file
- added jackson libs to parse geojson offline polygon file
- code to parse geojson - updated all map activities to listen for offline map parse complete, once complete a new 'offline' map type is available in the map type menu

fixes #4
Add Natural Earth attribution

fixes #1
Fixed a bug where onResume would create a new offline map.  This is probably the right thing to do, except the old offline map after onPause() was not removed and cleaned up.  Now cleaning up the offline map from each map activity in the onPause method.
Merge branch 'master' of https://github.com/newmanw/anti-piracy-android-app
Fixed offline map being loaded more than once.
Fixed a few more menus to show action bar icons correctly.
Added description to disclaimer buttons.
Removed unused constant for tablet launch.
Minified the offline map geojson file
Tablet map activity was calling clearMap which was causing offline polygons to be cleared in offline map.
add content description to disclaimer
Merge pull request #6 from newmanw/master

Offline Maps