Geocoding fixes

410332836fca89517fc39b17de8e75d050068cec is a one character patch!
Stone Soup was using version 2 of Google's geocoding api, but deprecation of that version was finalized in September, 2013 with the Google servers now refusing to provide a reply.

Fortunately, Geokit already had support for Google's v3 api -- hence the once character patch to switch to that.
This first commit is the only essential one of the bunch here in terms of fixing broken functionality.

Unfortunately, Geokit's 1.6.7 implementation uses the old maps.google.com hostname, which works for now but is also officially deprecated. Upstream has only partially fixed this.

The remaining three commits are cleanups related to these two points:
* When using bundle install, the geokit gem is installed that way and the vendor one is no longer in use
    test with $ ./script/console

    >> require 'geokit/version'
=> []
>> GeoKit::VERSION
=> "1.6.7"

* Geokit's google version 3 support does not require a Google api key and neither does Google. (version 1.6.7 doesn't even let you use an api key for a non-business Google account, the upstream version does, and even uses the correct google server when it doing so, but doesn't use the correct google server otherwise)