Remove pbr as a runtime dependency
Remove pbr as a runtime dependency

The pbr package is only a build time
dependency and as such should not be
in the requirements.txt requirements
file.

Change-Id: I5ee90767850c2caa4534f69b967f6dce6eca0de1

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