Allow loading of Jade options from package.json for command line builds.

This allows loading of jade options from `package.json` when doing a browserify build from the command line.  This relies on browserify-transform-tools, and you can read all about how it loads configuration [here](https://github.com/benbria/browserify-transform-tools/wiki/Transform-Configuration), but the upshot is you can add a section to your package.json that looks like:

    "browserify-jade": {"pretty": false}

and this will disable adding pretty whitespace to your jade files.