travis: Pushing master,centos,7 build
travis: Pushing master,centos,7 build

Since commit 3d573250525511f6c12a40ec9c5e628e451ea162, the push should be done on master instead of mimic.

Signed-off-by: Erwan Velu <dbf153a4f846e5c13692f4d75719ee25e7660abd@redhat.com>

ceph/ceph-docker,ceph/ceph-docker