Geo: fixes circle radius calculation

This change fixes the creation circle shapes o it calculates it correctly instead of essentially using the diameter as the radius.  The radius has to be converted into degrees but calculating the ratio of the desired radius to the circumference of the earth and then multiplying it by 360 (number of degrees around the earths circumference).  This issue here was that it was only multiplied by 180 making the result out by a factor of 2.  Also made the test for circles actually check to make sure it has the correct centre and radius.

Closes #7301
maybe reuse GeoUtils.EARTH_EQUATOR?