Update getCMSFields to leverage extend('updateCMSFields')

Update Locator.php to allow better FieldList control with $this->extend('updateCMSFields', $fields)
Update Location.php to allow better FieldList control with $this->extend('updateCMSFields', $fields)
Merge pull request #15 from nhorstmeier/master

Update getCMSFields to leverage extend('updateCMSFields')