Add browserify support via browserify-shim

This patch does a few things:

- adds browserify-shim as a dependency (necessary for browserify-cdn to be able to transform it)
- adds a `browser` field to point at the actual built file since obelisk uses globals
- assigns browserify-shim as a transform
- adds an npm script to output the browserified version for testing (gitignored, should never be published)

Sorry for the largely whitespace changes in package.json, but npm likes using 2 spaces when using the `--save` option. You can view this PR with `?w=1` in the URL to see only the _real_ changes.

The reason for all of this is that once this patch lands and a new version is pushed to npm, obelisk can be used in something like http://requirebin.com/ for easily shareable demos!

I wanted to add a test or two that verifies that everything is working properly, but there were no tests in the project and didn't want to make this PR too large (or drastic). If you'd like tests, just let me know and I can whip something up using [tape](https://github.com/substack/tape).