Updating GeoIPs provider to expect a single location response

One change to expect multiple locations returned by the service as proposed in PR #273 and merged at https://github.com/geocoder-php/Geocoder/commit/622ac5e88a7a1630d829a66a8b1d65d8d60021f9 seems not to be valid anymore.

The <a href="http://www.geoips.com/en/developer/api-guide">API Documentation</a> describes a single `location` xml element in accordance with the response i get from querying the service.

FYI ping @Thinkscape