Add icons and text to MapActivity to indicate the GPS fixes & satellites

Icon from https://www.iconfinder.com/icons/175171/gps_receiving_icon so if used
must include link to author's website: http://icons8.com/

Modified icon for the case of no fixes by removing semicircular lines.  Made
white and scaled for xxhdpi, xhdpi, hdpi, and mdpi.
Add latitude & longitude to the header bar
Add Cell and WiFi info to the bottom of the MapView
Merge pull request #729 from keverets/map-add-info

Add Information (GPS Status, Location, Cell Info, WiFi Info) to the Map
Add PathOverlay to the map, to draw the GPS track

Also, use a consistent color for the GPS dot and track.

Note that post OSMDroid-4.2, PathOverlay is deprecated, and OSMDroid
recommends using Polyline in the OSMBonusPack:

https://github.com/osmdroid/osmdroid/issues/40