Werk #267: Fixed auth.serials permission problem in check_mk standalone installation

In a standalone installation the path /usr/local/nagios/etc is not writable by the apache user.
The user management module tried to create a file /usr/local/nagios/etc/auth_serials.new and rename it to /usr/local/nagios/etc/auth_serials afterwards -> failed
The workaround is that no auth_serials.new file will be created on standalone installations. The user management module now directly writes in auth_serials.

To the list of all Werks