Replace home directory list with a dashboard

Summary:
Rough cut that still needs a lot of polish, but replace the directory list with
more of a dashboard type thing:

• Show "Unbreak Now", triage-in-your-projects, and other stuff that you're

supposed to deal with, then feed.

• Move tools a click a way behind nav -- this also lets us put more stuff

there and subtools, etc., later.

• Remove tabs.
• Merge the category/item editing views.
• I also added a light blue wash to the side nav, not sure if I like that or

not.

Test Plan:

• Viewed all elements in empty and nonempty states.
• Viewed applications, edited items/categories.

Reviewers: btrahan, aran

Reviewed By: btrahan

CC: aran, epriestley, davidreuss

Maniphest Tasks: T21, T631

Differential Revision: https://secure.phabricator.com/D1574