Inherit the greenpool default size
Inherit the greenpool default size

Change-Id: Ia2dc394a03c748e919f2251f618131daea9d5eca

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