Extract admin styles from mltshp repo

[bradchoate]

There are some new styles for the admin part of MLTSHP, saved to static/css/admin.css that should be extracted to mltshp-patterns, and should be published (along with other admin styles that are already in this repo) to a new admin.min.css bundle.

However, part of the new styles includes a set of rules for a tabbed interface that should be generalized in a way that it can be used for non-admin use. There's currently one tabbed interface on the public side of MLTSHP - the user settings area (however, presentation here is very different than the other, so it may not be possible to combine them, but I'm calling it out in case there is any sensible overlap).

Here's a screenshot of the tabbed UI used for user management:

One other thing that could use some cleanup -- several admin pages make use of a "admin-new-users" class (create-users.html, group-shake-list.html, group-shake-view.html, index.html, new-users.html, shake-categories.html, user.html)... so this class is misnamed as it isn't particularly specific to new-users.html.

[spaceninja]

@bradchoate one thing that would be helpful, since I don't have the MLTSHP app running, or access to the admin area — Could you attach some HTML with the markup for the admin pages, so we have examples in the pattern library to check these styles?

[bradchoate]

You should be able to go by the application templates themselves. The html that's in there is pretty much what is output... not like React-based templating that's written with one set of tags and outputs another. Most of the styles in admin.css are for templates/admin/user.html. A few were added for templates/admin/group-shake-list.html and templates/admin/group-shake-view.html.