Upgrading from an older samba4 installation.

* Compile the new version of samba4 by following the HOWTO, but do
  not install it yet, and do not run provision.
* Stop any samba process
* Backup your samba4 provision:
  go into the directory where your samba4 provision is stored (/usr/local/samba by default)
  do tar cf $HOME/backup.tar private etc var sysvol
* Go into the source4 dir
* run ./scripting/bin/upgradeprovision -s <path to smb.conf in samba4 install>
* do make install

This will do the minimum (safest) upgrade of the data.  

Runing upgradeprovision with --full will do a more comprehensive
upgrade of the data (including schema and display specifiers).  This
attempts to do a new provision, and to then copy existing data into
that database.