Merged cm_model_location_city_ip and cm_model_location_country_ip

- Added column "level"
- Added migration script, needs about one minute to run
- Refactored CM_Model_Location::_getLocationIdByIp() to _findByIp(), returning a CM_Model_Location
- Adjusted usages in MaxMind (import) and tests
- Not importing ip blocks for zip codes and regions yet
Imported IP blocks for regions and zip codes

- Added tests
Fixed IP block import for existing regions

- Added tests
Added tests for import of region IP blocks
Checked IP block overlapping

- Added tests
Merge pull request #1249 from fauvel/issue-1249

Import IP blocks for regions and zip codes