Summary:
Depends on D19073. Ref T13073. Give leases a normal header tag and try to wrangle their status constants a bit.
Also, try to capture the "status class" pattern a bit. Since we target PHP 5.2.3 we can't use `static::` so the actual subclass is kind of a mess. Not exactly sure if I want to stick with this or not. We could consider targeting PHP 5.3.0 instead to get `static::` / late static binding.
Test Plan: Viewed leases and lease lists, saw better and more conventional status information.
Subscribers: PHID-OPKG-gm6ozazyms6q6i22gyam
Maniphest Tasks: T13073
Differential Revision: https://secure.phabricator.com/D19074
