MapViewer, Actionbar fixes, Database Viewer UI & Fallback MCC Location

Increased Map Viewer default zoom level as it was too high, this should now provide a better display of the
current location.

Invalidated the Actionbar/Menu display whenever the main activity is displayed to ensure the correct icons
are displayed for the tracking indication.

Corrected the Signal Strength tracking indicator icon, this one is a good example of why I should not
code whilst drinking bourbon! :)

Tweaked the Database Viewer card display to use a darker colour scheme and gradient on the cards, I think
this looks 100x better the original white crappy display.

Map Viewer will now attempt a 3 step process to determine where to initially display the map:
1. Last location held in the location tracking database,
2. Last known location held by the device from either GPS or Network location service
3. **NEW** Based on current MCC the Map Viewer will move to the Capital City based on the MCC

The default locations are provided through the default_mcc_locations.csv file which is found in the
app/src/main/assets folder which lists Country, Mcc, Longitude and Latitude. These details are held within
a database table and populated whenever the database is upgraded. This detail can also be viewed through
the database viewer.