Refs #6180 - make sure the task label is set before the planning starts

With this fix, we can rely on the label not being nil until the
planning finishes.
Merge pull request #77 from iNecas/label-from-the-beginning

Refs #6180 - make sure the task label is set before the planning starts
Bump required dynflow version
Automatic commit of package [rubygem-foreman-tasks] release [0.6.5-1].