Allow hostnames to contain hyphen.
Currently hostnames cannot contain a hyphen ("-") anywhere.
This change allows domains to contain a hyphen, but not start or end with one.
See http://stackoverflow.com/q/2063213 for relevant discussion.
Merge pull request #7 from ryandjurovich/hostnames-with-hyphen

Allow hostnames to contain hyphen.
Merge branch 'master' into blank-domain-check
Removed Domain::blank? method and contiue to use Object.blank? in helper.rb
Instead we add a require to load helper.rb in Domain.class.rb
Allows rspec to run on just the Domain.class.rb file without error