This is needed before we can upgrade to flake8 3.3.0, as that version starts flagging these errors.
These files were modified by running:
autopep8 --select E305 --in-place -r <dir>
on the affected directories. I did it one dir at a time and verified the result after each.
MozReview-Commit-ID: FmlsfiKIbtr
This adds `.cron.yml` and a new mach command to interpret it. While
functionality is limited to nightlies right now, there is room to expand to
more diverse periodic tasks. Let your imagination run wild!
MozReview-Commit-ID: KxQkaUbsjQs
