Allow geocoder to work without an instance

* Don't assume there's a config.instance.extent to filter the results
* Move geocode-results-template from instance_base.html to base.html so it can be used without an instance

Also:
* Add and use utility webMercatorToLeafletLatLng()
* Alphabetize aliases in Gruntfile
Merge pull request #791 from RickMohr/geocode-help

Allow geocoder to work without an instance