Security update

Fixes Drupal Remote Dashboard - Critical - Weak encryption keys - SA-CONTRIB-2017-046

Improve key length handling
Always generate random keys
Store and transport keys in base64 encoded format

Fixes DrupalChat - Critical - Multiple vulnerabilities - SA-CONTRIB-2017-057

• #2893054: Create a new stable release, properly tagged from tip of 7.x-2.x

This release disallows OAuth protected responses from being cached.

See OAuth - Critical - Access Bypass - SA-CONTRIB-2017-056.

Fixes DrupalChat - Critical - Multiple vulnerabilities - SA-CONTRIB-2017-057

Fixes SMTP - Moderatley Critical - Information Disclosure - SA-CONTRIB-2017-055

Fixes SMTP - Moderatley Critical - Information Disclosure - SA-CONTRIB-2017-055