Add Recent label to Conpherence thread list

Summary: Fix 'No Conpherences' layout, add 'Recent' label to list.

Test Plan: test with and without a list of threads.

Reviewers: btrahan, epriestley

Reviewed By: epriestley

Subscribers: Korvin, epriestley

Differential Revision: https://secure.phabricator.com/D11569