Use six.text_type() instead of str() in sqlalchemy backend
Use six.text_type() instead of str() in sqlalchemy backend

Change-Id: Ie78d2890ce008f22c94e705dbb489838375d303d

junneyang/taskflow,jimbobhickville/taskflow,pombredanne/taskflow-1,jimbobhickville/taskflow,openstack/taskflow,openstack/taskflow,varunarya10/taskflow,junneyang/taskflow,varunarya10/taskflow,pombredanne/taskflow-1