SUSE-SU-2018:2561-1 Security update for cobbler

This update for cobbler fixes the following issues: Security issues fixed: - Forbid exposure of private methods in the API CVE-2018-10931, CVE-2018-1000225, bsc1104287, bsc1104189, bsc1105442 - Check access token when calling 'modifysetting' API endpoint bsc1104190, bsc1105440, CVE-2018-1000226...