add over quota exception handling for nominatim

Conflicts:
	lib/geocoder/lookups/maxmind_local.rb

Fix warnings

Also change name of configuration option from :licensed to :open.

Previously nil was being returned on API errors,
which caused un-helpful exceptions.

Update README.md: supported Ruby versions.

Add Rubinius and Ruby 2.1 in README.

Allow bing to search restricted by region

Add support for Nokia's here.com geocoder.

Don't throw errors when using SSL