mailman security and bug fix update

3:2.1.15-30 - Resolves: 1599692 - Sanitize input on listinfo page CVE-2018-0618 3:2.1.15-29 - Resolves: 1611689 - Trim long text in 'no such list' messages 3:2.1.15-28 - Resolves: 1718180 - Try to decode member name first 3:2.1.15-27 - Related : 1545973 - Bump release to override rhel-7.4.z versi...