s4:provision - rework the "guess_names" and "make_smbconf" method

s4:provision - rework the "guess_names" and "make_smbconf" method

- Cleans it up from unnecessary "lower()/upper()" and parameters which can be
  derived through "lp" calls.
- Substitute the "HOSTNAME" caption in the "smb.conf" templates with
  "NETBIOS_NAME" which fits better.
- Now the "realm" and "domain" parameter of the provision are totally case
  insensitive and the script itself up/downcases them appropriately depending
  on the use (e.g. "realm" upcase for KERBEROS, lowcase for DNS domainname).