Change default status to 'all' in DifferentialRevisionList

Summary: Makes it easier to discover the list of all revisions for a user.

Test Plan:
Opened up /differential/filter/revisions/, and saw that it defaulted
to status of all. Clicked between tabs, and it stayed on all. Selected
open, it only displayed open revisions, including as I switched between
tabs.

Reviewers: epriestley, jungejason

Reviewed By: epriestley

CC: aran, epriestley

Differential Revision: https://secure.phabricator.com/D1278