Migrate common setups as role/*

origin: https://pfs.ipmu.jp/wiki/System/install/linux-base-stretch

roles

• common: system account, shell, common package (screen, vim), LDAP, network storage
• cron-apt
• ntp
• munin
• exim4

note: might be better to separate common role into individual ones.

followings will be filed as separated tickets

• physical host controls (ipmi, lm-sensors, etc.)
• libvirt environment, network
• NFS server