Create badge/pill design system

Created by: joe-watkins

As noted in https://github.com/a11yproject/a11yproject.com/issues/513#issuecomment-324658307 we are needing a cool / easy-to-use badge/pill design system integrated into the site.

Will try this system out on the patterns page. Needs to be flexible so that it works in other areas of the site ;)