Remove the need to specify the pbr hook

If you're running pbr codepaths, you want the hook. There is no need
to say "pbr=True" in setup.py and then to list the hook in setup.cfg
now that d2to1 is in the tree.

Change-Id: Ie33d3e08d5a4133f5caf2613859919ce4f02c4a0
Merge "Remove the need to specify the pbr hook"