rabbitmq / centos-odcs: we need a centos-odcs user
    
    This was hidden away in the odcs playbook in fedora infra, so I missed
    that we didn't make it in the odcs role, which is where we copied the
    things for the centos odcs application. So, add it in there so it makes
    a centos-odcs user.
    
    Signed-off-by: Kevin Fenzi <kevin@scrye.com>