R1:1d00bc918019

Clean up nux state with durable column

Summary: Remove policy icons from durable column, create a basic nux layout and style.

Test Plan: leave all rooms, pop open chat, see helpful text and button.

Reviewers: epriestley

Reviewed By: epriestley

Subscribers: Korvin

Differential Revision: https://secure.phabricator.com/D16655