Fix install script for CentOS - avoid useless check-update command, avoid error on SELinux command, use GPG checks
Merge branch 'branches/rudder/2.4' into branches/rudder/2.6
Merge branch 'branches/rudder/2.6' into branches/rudder/2.7
Merge branch 'branches/rudder/2.7' into branches/rudder/2.8
Merge branch 'branches/rudder/2.8'