Fix #163 - Add setting to change distance units

* Includes an automatic option (default) that attempts to guess metric/imperial based on current locale
Fix #168 - Get map zoom as float
Fix #136 - Center map on user location only if region changed
Merge pull request #164 from CUTR-at-USF/issue163-PreferredUnits

Fix #163 - Add setting to change distance units
Merge pull request #169 from CUTR-at-USF/issue168-ExceptionOnOrientChange

Fix #168 - Get map zoom as float
Merge pull request #170 from CUTR-at-USF/issue136-MapRecenter

Fix #136 - Center map on user location only if region changed