Use fa 4.0.4-wip branch to, see #113

Font Awesome master uses `component.json` instead of `bower.json`, which trips
up `grunt-bower-install`.

See: https://github.com/FortAwesome/Font-Awesome/pull/2344
Merge pull request #19 from tlvince/bug/font-awesome-grunt-bower-install

Use fa 4.0.4-wip branch to, see #113