Possible work-around for gherkin require issues

This is one possible solution for our `require` conflict in `fxa-js-client-old` or the library formerly known as gherkin. This removes `fxa-js-client-old` from the require.js dependency flow in `main.js` and makes it globally accessible. It is now being included in `index.html` and built into the distributed `main.js` file via the grunt build tools.

This is only necessary if we can't get a stand alone version of gherkin working, but since this works, I figured I'd submit it for consideration. This might also let us move on from worrying about old client and work on new client. Let me know what you guys think...