Conpherence - fix a few bugs

Summary:
1) make the page title and uri update appropos to selected widget 2) make a behavior actually listen 3) fix the css so the button can always be clicked to edit metadata

Ref T3035 as I was trying to repro the metadata edit bug there and couldn't.

Test Plan: made the window small enought to have all the widgets visible and be in "device mode". noted page title and uri updated correctly from Conpherence and /conphernece/ to Thread Title and /conpherence/$id/ when toggling between thread list and current thread. made the window small enough to have the title and subtitle fields overlap with the edit button.

Reviewers: epriestley

Reviewed By: epriestley

CC: aran, Korvin, chad

Maniphest Tasks: T3035

Differential Revision: https://secure.phabricator.com/D5754