Dont try to reverse lookup lat/lng

If people already specify a latitude/longitude value, don't try to reverse lookup it, because it may lead to relevant offsets.

For instance: 46.043118, 8.810928 is converted to 46.05832, 8.80685, which is 1.7 Km (more than 1 mile) away.

Bugtracker: http://www.concrete5.org/developers/bugs/5-6-3/google-maps-block-offset-when-using-coordinates/