Add support for geometries

So far there was only support for bounding boxes. With this change it
is now possible to use the legacy API of emitting a GeoJSON geometry.

Change-Id: I05e39ab9c57457f1a6aecd40014bf4bdb3bbac2f
Reviewed-on: http://review.couchbase.org/40138
Reviewed-by: Volker Mische <volker.mische@gmail.com>
Tested-by: Volker Mische <volker.mische@gmail.com>