R1:8d8f983f6af5

Modernize Dashboard UI and code

Summary: Pulls everything over to two column UI and new edit pages. Removed history view and consolidated some pages.

Test Plan: New Panel, Edit Panel. New Dashboard, Edit Dashboard, View Standalone pages.

Reviewers: epriestley

Reviewed By: epriestley

Subscribers: Korvin

Differential Revision: https://secure.phabricator.com/D15588