kernel: use packaging.GitbuilderProject to talk with gitbuilder.
kernel: use packaging.GitbuilderProject to talk with gitbuilder.

This fixes issue: http://tracker.ceph.com/issues/12795

Signed-off-by: Andrew Schoen <1bb641dc23c3a93cce4eee683bcf4b2bea7903a3@redhat.com>

SUSE/teuthology,caibo2014/teuthology,ceph/teuthology,robbat2/teuthology,dmick/teuthology,dmick/teuthology,dreamhost/teuthology,SUSE/teuthology,ceph/teuthology,ktdreyer/teuthology,robbat2/teuthology,dreamhost/teuthology,ktdreyer/teuthology,SUSE/teuthology,dmick/teuthology,caibo2014/teuthology