Rgeo support (rgeo/activerecord-postgis-adapter)

[kofronpi]

Objects with a geom column from a spatial database (e.g. postgis with https://github.com/rgeo/activerecord-postgis-adapter are dumped, but the geom seems to be incorrect.

Example: https://gist.github.com/kofronpi/ebade6c9ef49369253a2380b59b77ca8

I will investigate further and edit this issue to explain more.

[kofronpi]

See #116