otrs.SetPermissions.pl: Added parameter to follow symlinks

Hi Martin,

in some cases / for some OTRS installations it's needed to follow symlinks for setting the right permissions. So I added the parameter 'symlinks' to do so. The old, non-syslink-following behavior is still the default.

The old implementation (see comment '# append / to follow symlinks') doesn't work. I use the File::Find option follow to really follow symlinks.

Greetings from Berlin,
Thorsten