Security update

Fixes Organic groups - Moderately Critical - Access bypass - DRUPAL-SA-CONTRIB-2016-023

Changes since 7.x-2.8:

• Improve membership subscription

Multiple bugfixes, features and a security hardening.

Security hardening: #2706793: Insufficient filtering of unit symbol

Bugs:

Fixes Boost - Moderately Critical - Information Disclosure - SA-CONTRIB-2016-021

Fix Data leakage via the form cache

Fixes Features - Less Critical - Denial of Service (DoS) - SA-CONTRIB-2016-020

Changes since 7.x-2.8:

This is a security release improving the access control of product SKU / title lists returned by the Commerce Product module for use in the product reference field's autocomplete widget. For more information, refer to the SA-CONTRIB-2016-019 security advisory.