FreeBSD: VID-9e50dcc3-740b-11e6-94a2-080027ef73ec (CVE-2016-7123): mailman -- CSRF hardening in parts of the web interface

The late Tokio Kikuchi reported: We may have to set lifetime for input forms because of recent activities on cross-site request forgery (CSRF). The form lifetime is successfully deployed in frameworks like web.py or plone etc. Proposed branch lp:~tkikuchi/mailman/form-lifetime implement lifetime in admin, admindb, options and edithtml interfaces. [...] The web admin interface has been hardened against CSRF attacks by adding a hidden, encrypted token with a time stamp to form submissions and not accepting authentication by cookie if the token is missing, invalid or older than the new mm_cfg.py setting FORM_LIFETIME which defaults to one hour. Posthumous thanks go to Tokio Kikuchi for this implementation [...].