Add a Gemfile
Add jasmine gem so we can add some JS tests.
After running `jasmine init`.
Do not install phantomjs automatically.

I think both @chrisroos and I already have it installed on our local machines,
so there doesn't seem much point in doing this.

Note that there was a missing underscore in the commented-out code. This has
been fixed in the repo, but not yet released.
Add a sample JavaScript spec.
Make default rake task run the JS tests via Jasmine.