Bug 1070001 reorg stylus tags

All tags now use same class ".tags".

There is a modifying class ".tags-small" for the tags in the wiki footer.

There is a .tags_tagit file to extend this with over-rides for the jQuery UI plugin.

Things that are not tags (list of interests on profile page) no longer use the class ".tags".

Pages for testing:
https://developer-local.allizom.org/en-US/profiles/stephaniehobson/
https://developer-local.allizom.org/en-US/profiles/stephaniehobson/edit
https://developer-local.allizom.org/en-US/docs/Web/HTML/Element/progress$edit
https://developer-local.allizom.org/en-US/docs/Web/HTML/Element/progress
https://developer-local.allizom.org/fr/docs/Web/HTML/Element/Progress$edit
https://developer-local.allizom.org/ar/docs/Web/Apps/Quickstart/Design/%D9%85%D9%81%D9%87%D9%88%D9%85_%D8%AA%D8%B7%D8%A8%D9%8A%D9%82_%D8%B9%D8%B8%D9%8A%D9%85%24edit
https://developer-local.allizom.org/en-US/learn/css
https://developer-local.allizom.org/en-US/badges/badge/learner
https://developer-local.allizom.org/en-US/demos/detail/bubble-shooter

Will need a re-base after #2762 lands.