Move domaincontroller to directory services, also rely on samba_server

- Add domaincontroller to directory services choices
- Modify notifier cifs methods to use samba_server
- Modify notifier domaincontroller method to use directory services
  shell scripts
- Modify directory services class to be aware of domain controller class
- Modify startup and shutdown accordingly
- Remove from view
- Remove from core services page
- Add directory services shell scripts
- Replace all 'samba' service references with 'samba_server'
- Modify kerberos startup to be samba4 aware
- Modify pam and nsswitch to also be samba4 aware
- Modify rc.conf.local to set the proper rc variable for samba_server