This commit adds the Data Science Toolkit as a lookup type.  The DSTK behaves identically to the Google Maps API with the exception that it can be run behind your own firewall.  More information about this tool can be found here: http://www.datasciencetoolkit.org/

instead of inferring from response length. This is less than ideal but
it fixes issue #396 and, given what appears to be MaxMind's inconsistent
response lengths, it may not be possible to do much better.

Now it is necessary to specify which service is being used:
  Geocoder.configure(:maxmind => {:service => ...})
where '...' is one of: < :country | :city | :city_isp_org | :omni >

Make Geocoder.configure accept a hash (now preferred) and add
Geocoder.config method (for reading config). Deprecate old syntax.

This requires changing the way stubs work, so that they only simulate
actual HTTP calls, not cache hits.

Also move API key config to separate method.

Allow lookups to define a cache key (defaults to the query URL) and
define Yahoo's as the non-OAuth-encoded request URL.

Add test and display Yahoo's error message in warning.

previously the mapquest service was relying on an outdated url
that was just defering to the Nominatum service. This commit
brings in supported Mapquest API support for v1 of their API.

It supports the open (free) tier of the API along with the
licensed version of the service.

Auto-detect which one is being used. It's necessary to continue
supporting 1.0 because of the existing data in people's caches.
See discussion: http://github.com/alexreisner/geocoder/pull/307

"Results" key is now "Result" and is not an array when only one result.
Update code and response fixtures to reflect this.

in request to geocoding service.

Also move some lookup-related methods to Geocoder::Lookup module.

For consistency with rest of code.

Instead use an array for key, client, and channel.

Removed set_defaults from all tests and replaced with teardown to reset the defaults.

Signed-off-by: James McCarthy <james2mccarthy@gmail.com>