Use Less sourcemaps

The issue turned out to be the `map` option in `autoprefixer.js`. Setting it to `true` results in `grunt-autoprefixer` generating a new base64-encoded sourcemap that doesn't play well with our set up. Leaving it *undefined* (that is, removing the property altogether) tells it to update the source map that was previously generated by `grunt-contrib-less`.

I also added a couple of the updated cf components to the test file.

Resolves cfpb/capital-framework#45.