Sort out application crumbs in new repository edit workflow

Summary: Ref T2231. Crumbs in the Diffusion edit workflow are a bit wonky, with stuff like "rP (master)" which isn't very useful and no link back to the main "Edit" page. Make them consistent across all the screens.

Test Plan: Loaded a bunch of these screens and saw sane crumbs on all of them.

Reviewers: btrahan

Reviewed By: btrahan

CC: aran

Maniphest Tasks: T2231

Differential Revision: https://secure.phabricator.com/D7407