Add support for simpler Lat/Long values

In this CL, we add two public static final Strings to MetadataReader. I
use these to put in an "extras" bundle into our highest level bundle.
Within that extras bundle is the Latitude and Longitude values, if
available.

Bug: 63906073
Test: In Place
Change-Id: I1feccb4444d6525f9bc8bddfe8cc73b098e0b90e