This is to fix a downstream issue between nodepool and
diskimage-builder pip dependencies. Since nodepool depends on
diskimage-builder, it would be nice to have common depends.
We also bump hacking to deal with pbr version issues.
Change-Id: I0efa395bc66c9e50bfe4a13e971232ad9184ad48
Signed-off-by: Paul Belanger <pabelanger@redhat.com>