Hard-code and unify "more applications" in Phabricator

Summary:
This is mostly intended to simplify D2323.

We currently allow users to edit and customize the links on the homepage, but as far as I know no one actually does this (no one complained when we redid the homepage earlier this year) and it creates a lot of mess in the database patches and quickstart dump. After D2331, this is the only data we load in the patch files. The patch files are also a mess with respect to this data and have various different versions of it.

Also the current UI is just kind of bad, it stretches stuff across too many screens and is generally ungood. Nuking this lets us nuke a lot of code in general.

(In the long term, I think we'll move toward an "application" model anyway, and this stuff will go away sooner or later.)

I'll add a drop-database patch some time later, just in case anyone does actually use this, so they can get their data out of MySQL.

Test Plan: Looked at home page, clicked "More Stuff", got a single list of other apps/things.

Reviewers: btrahan, vrana, edward, jungejason

Reviewed By: jungejason

CC: aran

Maniphest Tasks: T345

Differential Revision: https://secure.phabricator.com/D2332