Fixing Problem with Geolocating Canadian Addresses

We were experiencing an issue with geolocating Canadian addresses, which was causing an error 500 on the group search map. See https://www.pivotaltracker.com/story/show/48860165

Geokit::GeoKit::Geocoders::MultiGeocoder.geocode seems to choke on Canadian addresses for some reason, and Geokit::Geocoders::CaGeocoder.geocode wasn't doing any better until I brought the request URI up to speed with the current API docs for geocoder.ca: http://geocoder.ca/?premium_api=1

I also updated/cleaned up the unit tests so that they all pass.