conpaas-xtreemfs: wait for storage device before mounting, set opennebula volumes as persistent


git-svn-id: svn://svn.forge.objectweb.org/svnroot/contrail/trunk/conpaas@5306 ef35cc4a-2640-4bbf-98bc-65920db7d8ae
conpaas-xtreemfs manager: set_service_snapshot initial implementation


git-svn-id: svn://svn.forge.objectweb.org/svnroot/contrail/trunk/conpaas@5307 ef35cc4a-2640-4bbf-98bc-65920db7d8ae