Fix missing fonts

[davidfischer]

If you load a docs page like https://docs.readthedocs.io/en/latest/ you see that there are some missing fonts in the console. Some of these show up as CORS issues but that is a red herring because the request 404-ed.

Access to Font at 'https://media.readthedocs.org/fonts/fontawesome-webfont.woff2?v=4.7.0' from origin 'https://docs.readthedocs.io' has been blocked by CORS policy: No 'Access-Control-Allow-Origin' header is present on the requested resource. Origin 'https://docs.readthedocs.io' is therefore not allowed access. The response had HTTP status code 404.
Access to Font at 'https://media.readthedocs.org/fonts/Lato-Italic.ttf' from origin 'https://docs.readthedocs.io' has been blocked by CORS policy: No 'Access-Control-Allow-Origin' header is present on the requested resource. Origin 'https://docs.readthedocs.io' is therefore not allowed access. The response had HTTP status code 404.

This PR fixes this issue. The 2 fonts included with this PR come directly from bower.

Replaces #3602