Capture pip logs on pbr integration test job

Change-Id: I42e086f9dfa885a55cfcdd99b301b5af1709dda9
Reviewed-on: https://review.openstack.org/36145
Reviewed-by: James E. Blair <corvus@inaugust.com>
Approved: Clark Boylan <clark.boylan@gmail.com>
Reviewed-by: Clark Boylan <clark.boylan@gmail.com>
Tested-by: Jenkins