CIDEVSTC-99 - WKT handling by datastore/Postgres

M112 T133 - WKT handling by datastore/Postgres

Implements a WKT string search capability to datastore/Postgres (using PostGIS)

Handles all valid WKT string and the concept of a circle with radius as a point with a buffer to desired radius. Example {'wkt':'POINT(-70 40)', 'buffer':1.0} creates a circle centered on 40N,70W with a radius of 1.0 degrees.