Display day of week in dates

Summary:
I've found it quite useful to know day of week of most displayed dates.
This is useful in periodic workflows (e.g. cut on Sunday, push on Tuesday).

It adds the day only to recent dates to save some space (similar approach as ls -l).

Test Plan: /

Reviewers: epriestley

Reviewed By: epriestley

CC: aran, epriestley

Maniphest Tasks: T1034

Differential Revision: https://secure.phabricator.com/D1984