Add more useful `__str__` to redis job
Add more useful `__str__` to redis job

The information about the sequence and the owner_key is
useful for debugging and for interacting with redis if
the owner key ever needs to be manually removed.

Change-Id: Ibe751d15938a2bcb83fb057f4c139f8f0022a60b

pombredanne/taskflow-1,junneyang/taskflow,jimbobhickville/taskflow,openstack/taskflow,junneyang/taskflow,jimbobhickville/taskflow,openstack/taskflow,pombredanne/taskflow-1