DATAMONGO-858 - Add support for common geospatial structures.

Prepare issue branch.
DATAMONGO-858 - Add support for common geospatial structures.

Set dependency to SD commons branch with common geo spatial structures.
DATAMONGO-858 - Add support for common geospatial structures.

Backed the geo spatial structures of SD MongoDB by the new geo spatial structures in SD commons. Deprecated the MongoDB geo spatial types to make users aware that we're going to remove them in one of the following development iterations. Added custom conversions for basic geo spatial types.
DATAMONGO-858 - Add support for common geospatial structures.

Adjusted geostructures according to code review.
Moved geo structure converters from MongoConverters into GeoConverters.
Added deprecation hints.
We deliberately choose not to let Circle extends CMNS geo.Circle since it would break clients that use the legacy Circle API (getRadius() returns a Distance in CMNS where as it returns a plain double in Mongo).