Tabbed case detail

FB129673

Technical spec: https://confluence.dimagi.com/display/ccinternal/Tabbed+Case+Detail

Not-so-technical spec: https://docs.google.com/a/dimagi.com/document/d/1MiGqDJA59ZN9ycEWuq5ObVc9lhpVe0TgwCAfInhDzF8
That's a good point, this ought to support text + image + audio. Made a subcase, will do in another PR.