Change lat/long predicates to use Basic Geo (WGS84 lat/long) Vocabulary

[vantuyls]

[moved from OD1] - OregonDigital/oregondigital#1154

The current lat/long predicates are from the EXIF vocabulary, and I think a better fit is the Basic Geo (WGS84 lat/long) Vocabulary: https://www.w3.org/2003/01/geo/
EXIF is closely tied to pictures, and comments in that schema specify that values should be in 'degrees, minutes and seconds' which we've moved away from. https://www.w3.org/2003/12/exif/

http://www.w3.org/2003/01/geo/wgs84_pos#lat
and
http://www.w3.org/2003/01/geo/wgs84_pos#long

This will involve changing predicates on all existing records too and reindexing them.