Show only one "reload" popup, use 'alert' style, click to reload

Summary: Use the features from D2758.

Test Plan: Updated T1 with two browser windows pointing at it, verified reload appeared, only one reload, and it appeared with 'alert' style.

Reviewers: jungejason, vrana

Reviewed By: jungejason

CC: aran

Maniphest Tasks: T944

Differential Revision: https://secure.phabricator.com/D2781