Add `location` parameter and polygon support for queries and facets

See https://github.com/hbz/lobid/issues/88

Pass space delimited `lat,lon` points describing the polygon.

Deployed to staging:

http://test.lobid.org/resource?format=full&author=136378153&location=52,6.5+52,7+51,6.5+51,7
http://test.lobid.org/resource/facets?field=@graph.@type&location=52,6.5+52,7+51,6.5+51,7