Add 'rollback' command as allowed for failure_action
Add 'rollback' command as allowed for failure_action

Signed-off-by: Nikolay Murga <e274eeff768c6396088ec6eb091f4bf4d47ab1e0@murga.kiev.ua>

vdemeester/docker-py,docker/docker-py,docker/docker-py,youhong316/docker-py,funkyfuture/docker-py,youhong316/docker-py,vdemeester/docker-py,funkyfuture/docker-py