The previous implementation used the EarthTools Webservices, but this
website has been down for a few months now. This replacement uses
the Sunset-Sunrise API. (See also: http://sunrise-sunset.org/api.)
* Rename the Hued class to Hued::Engine so that Hued can be the containing
module
* Split off the version to lib/hued/version.rb
* Undo Rule being a nested class of Engine