Fixed CM_Model_Location::findByCoordinates()

- Converted latitude to radian before calculating its cosine
- Swapped meters per degree calculation for longitude and latitude
- Introduced class constant for EARTH_RADIUS, which is being re-used in getDistance()
- Used mysql function Point() directly instead of GeomFromText()
Added test for CM_Model_Location::findByCoordinates()
Fixed CM_Model_Location::findByCoordinates()

- Fixed meters per longitude degree calculation
Merge pull request #1067 from fauvel/issue-1067

Rural canada: Cannot find a location by coordinates `55.573038859345` / `-110.8104539943`