Implement GeoJSON

[george-oakling]

As GeoJSON is standardized format, let us make the import of markers in such a format.

Docs:

• https://storage.googleapis.com/maps-devrel/google.json
• http://googledevelopers.blogspot.cz/2014/03/maps-made-easier-geojson-in-javascript.html
• ...

[george-oakling]

All markers and map features are done in GeoJSON format. Woohooo/