Reorganize/rearrange site configurations

let's reorganize site specific configuration file as service oriented.

• exim4_smarthost to mail.smarthost
• have ldap dict
• munin_cidr and cron_apt_hour to dict (e.g. munin.cidr, cron_apt.hour)

also consider to reorg nfs, like elastic.storage_nfs and virt.nfsdisk into nfs as each dict.