Upgrade phabricator to libphutil v2

Summary: Mechanical changes from D2588. No "Class.php" moves yet.

Test Plan: See D2588.

Reviewers: vrana, btrahan, jungejason

Reviewed By: vrana

CC: aran

Maniphest Tasks: T1103

Differential Revision: https://secure.phabricator.com/D2591