[teampractices] Please ALWAYS set Sprint start and end dates when marking a Phabricator project as a sprint

[Andre Klapper]

Setting dates currently requires reloading the "Edit Project" page again
so I understand it is not very obvious.

If not set, https://phabricator.wikimedia.org/project/sprint/ just
displays an error about your project instead of the list of sprints.

(I've just fixed Gather, Fundraising and Team-Practices sprint projects,
and I have had to fix a few more projects in the last days.)

Thank you,
andre
-- 
Andre Klapper | Wikimedia Bugwrangler
http://blogs.gnome.org/aklapper/