Slightly better "Simple Dashboard"

Summary: Fix copy for installing dashboard, add a revision panel, and change the default name to make it easier to find. Ref T12174

Test Plan: Go to dashboards, click New, then Simple. Visit home and install my dashboard

Reviewers: epriestley

Reviewed By: epriestley

Subscribers: Korvin

Maniphest Tasks: T12174

Differential Revision: https://secure.phabricator.com/D17277