* Add ip-api.com (ip lookup) support

This service returns better coordinates for Europe than other free ip lookup services available in geocoder.

* Clean the results class

Remove default responses for fields.

* Remove checking fields in url query

API already handles unknown fields, so this check is unnecessary.

* Add a test for using parameters directly in search method

No longer needed now that :yahoo lookup is gone.

TimeoutError is deprecated in Ruby 2.3.0. It has been an alias for
Timeout::Error starting in Ruby 1.8.0, and should be safe to replace.

The Yahoo BOSS Placefinder API is being discontinued.

https://developer.yahoo.com/boss/placefinder/

safe_location and location should not rely on the same variable,
otherwise calling one before the other will yield unexpected results
and could even cause a security risk if location is called before
safe_location

Not pretty, but it fixes out-of-the-box verbosity issues (see GH #881).

Test was failing for irrelevant reasons.