Use ceph.com mirror instea of github for ceph-qa-chef on VPS.
Use ceph.com mirror instea of github for ceph-qa-chef on VPS.

Github.com is unreliable so use the ceph mirror instead.

Signed-off-by: Sandon Van Ness <a38d61b815b8053a15c463c80449b5c080334ec7@inktank.com>

t-miyamae/teuthology,tchaikov/teuthology,zhouyuan/teuthology,michaelsevilla/teuthology,dmick/teuthology,ceph/teuthology,zhouyuan/teuthology,michaelsevilla/teuthology,robbat2/teuthology,caibo2014/teuthology,dmick/teuthology,dmick/teuthology,ceph/teuthology,caibo2014/teuthology,dreamhost/teuthology,ktdreyer/teuthology,yghannam/teuthology,ivotron/teuthology,robbat2/teuthology,SUSE/teuthology,tchaikov/teuthology,yghannam/teuthology,SUSE/teuthology,dreamhost/teuthology,t-miyamae/teuthology,SUSE/teuthology,ivotron/teuthology,ktdreyer/teuthology