Fix meeting_id in fedmsg messages published as reminders

Should fix https://github.com/fedora-infra/fedmsg_meta_fedora_infrastructure/pull/79
Thanks to @ralphbean for finding this :)
Add missing docstrings in the cron script
Add missing warnings import in the cron script
Remove un-used imports from the cron script
Adjust variable name
Merge pull request #112 from fedora-infra/fedmsg_fix

Fedmsg fix