openstack-full: add missing packages for RHEL7

Some packages need to be downloaded in EPEL for now.
The difference between 6.5 & 7 now is "cman" package which is not
packaged in 7 release.
openstack-full: check monitoring pkg on RH/CentOS

Check that monitoring packages are installed on RH/CentOS.

Signed-off-by: Emilien Macchi <emilien.macchi@enovance.com>