DATACMNS-437 - Add basic reusable geo structures.

Prepare issue branch.
DATACMNS-437 - Add basic reusable geo structures.

Moved and retro-fitted the basic geo structures from SD MongoDB into SD Commons. This will serve as the foundation for more reusable geo spatial functionality in other SD modules.
Adjusted equals methods to support subtypes in other SD modules.
Added convenience ctor to Polygon.
Removed MongoDB specific tuple representation (asList()).
Removed Shape marker interface.
Revised geo structures. Renamed spanning points of Box to be first and second because some stores could have a different meaning of the spanning points.
Changed radius field of circle to be a Distance (value + metric).
Added additional mitigation constructor to Circle.