shadow/TODO

ALL:
- move base passwd/shadow/group/gshadow operation to module for allow write
  diffrent backend modules for db, NIS, LDAP and others. Default backend it
  will be goot if will be choosen depending on /etc/nsswitch.conf and allow
  overwride this by -r <repository> options (where the <repository> can be
  file, db, nis nisplus, ldap .. like on /etc/nsswitch.conf in service column).
  passwd have old piece of code with handling -r option and it will be good
  finish this and propagate on other shadow tools for allow operate on other
  user databases by well known tools.

- useradd:
  - add handle create user mail spool in maildir format.

- add handle -n switch in groups and id command for allow query is
  group/user with specified id/gid exist - this will be very useable
  on automation in packages for quoery/check is group/user exist in system
  or not,

- groupmems: 
  - need some work on add PAM and i18n support.

- userdel:
  - add backup option on remomove user resources,
  - add lookop and remove per user group.

- passwd:
  - check combination of options (e.g. -u/-l)

Documentation:

- documment in pt_BR, ja man pages -s {pw,grp}ck option,

- document -o option in ja man page,