Update counties database

New counties database that includes adjacent counties
Add isNull() and equals() functions

Adds functionality for checking whether a LatLng contains a “null”
value (0,0) and functionality for checking equivalence.
Add DatabaseQuery class

Add a generic class that will pull a database out of the apk and open
it for use.
Add CountyQuery class

Add a class to interface with the counties database.
Add RadarSiteQuery class

Add a class to interface with the sites database.  Also removes the now
unnecessary SiteListHelper class.
Make private class members public

Make the previously private values for LatLngBox public for all classes.
Add documentation