R1:809646c8d2e9

Unprototype Almanac

Summary: Fixes T10449. Almanac doesn't do a whole lot for the average user, but is in good shape technically and works well, and exposing it in the cluster won't let installs destroy themselves now.

Test Plan: Re-read documentation; grepped for `TODO` (there are a couple, but reasonable to push off); browsed around all the UI things (new two-column looks great), called API methods.

Reviewers: chad

Reviewed By: chad

Maniphest Tasks: T10449

Differential Revision: https://secure.