create a helper function to install plugin priorities

Signed-off-by: Alfredo Deza <alfredo.deza@inktank.com>
if adjusting repos, install yum priorities

Signed-off-by: Alfredo Deza <alfredo.deza@inktank.com>
add the priority line to the repo files

Signed-off-by: Alfredo Deza <alfredo.deza@inktank.com>
add a remote helper function to set priorities in ceph.repo

Signed-off-by: Alfredo Deza <alfredo.deza@inktank.com>
set the right priorities in centos installs for ceph.repo

Signed-off-by: Alfredo Deza <alfredo.deza@inktank.com>
Merge pull request #197 from alfredodeza/8533

set the right priorites for the ceph.repo file