Add package for rbenv-ruby-1.9.3-p545

Not a security update.  Details here:
https://www.ruby-lang.org/en/news/2014/02/24/ruby-1-9-3-p545-is-released/
Merge pull request #27 from alphagov/rbenv_ruby_193_p545

Add package for rbenv-ruby-1.9.3-p545