`phantomjs-binaries` missing from bundle

[tristanm]

When running the specs I get the following error:

phantomjs-binaries is not part of the bundle. Add it to Gemfile. (Gem::LoadError)

Adding s.add_development_dependency 'phantomjs-binaries' to the gemspec fixes this but not sure if I'm missing something?

It's a bit too trivial for a pull request!