Add the ability to get point geometry from lat/lon fields in the view or SPARQL results

[jkerr5]

Instead of requiring the connector to retrieve the documents to extract point geometry, point geometry data should be able to be extracted and built from fields in a view or SPARQL query result.

The feature service descriptor needs to be able to specify how to get the geometry from the fields. It should look something like:

"geometrySource" : {
  "fields" : {
    "lat" : "lat",
    "lon" : "lon"
  }
}

[jkerr5]

This is implemented in the code but there are no test cases or documentation for it yet.