Merge pull request #88 from Sysnove/hosts

Replaced all by the list of host groups to be able to run the playbook with non-ceph servers.
Moved variables into "defaults" directory of each role, and commented the ones in group_vars.
Added dummy variable because ansible is not happy when there is no variable in group_vars files.
Moved OSD directory variables into defaults.
Added some keys to be able to have information from OSD nodes.
Updated group names according to Sysnove name layout.
Finished renaming server groups according to Sysnove inventory.
Added firewall configuration.
Accept Ceph-clients in shorewall rules
Added firewall tag
Whitelist
Allow devices to be partition instead of disks (used for some physical servers with a sigle disk for system and storage).