spec: sogo user as a system user, perms fixes

Create the sogo user as a system user
Use %attr() to set directory permissions instead of chown/chmod
Use more restrictive permissions for the log and spool directories
whitespace (tabkill)
whitespace (tabkill)
Rewrite useradd for debian packages

Add the sogo user as a system user
Create and/or fix the permissions/ownership of various directories when
installing or upgrading the package.
Use 'sogo' group instead of 'adm' in init script

This matches what the package preinst script does.
test-sogo-tool.py: Use sudo instead of su -
NEWS: Add note related to sudo -u sogo usage
Add note about 'requiretty' in sudoers file
Merge branch 'fix/1470_sogo-system-user'