Fixes SA-CONTRIB-2015-071 - Simple Subscription - Cross Site Scripting (XSS)
See SA-CONTRIB-2015-054 - SMS Framework - Cross Site Scripting (XSS).
Changes since 6.x-1.8:
Development snapshot for the 6.x-2.x branch. See the Agenda project page and the 6.x-2.0-beta1 release notes for more information on this branch.