Add a "tabs" dashboard panel type
Summary:
Ref T4986. Allows you to create a dashboard panel out of dashboard panels.
bwahaha
Test Plan:
{F155472}
{F155473}
Reviewers: chad, btrahan
Reviewed By: btrahan
Subscribers: epriestley
Maniphest Tasks: T4986
Differential Revision: https://secure.phabricator.com/D9141