Make ActionList on PHUIDocumentView always a dropdown menu

Summary: Gives back 160px of document space, makes Phriction easier to read. Moves ActionList into menu

Test Plan: Review Phriction Actions Menu, Edit Document, etc. Test mobile, tablet, desktop breakpoints.

Reviewers: btrahan, epriestley

Reviewed By: epriestley

Subscribers: Korvin, epriestley

Differential Revision: https://secure.phabricator.com/D12375