Recommended Heroku setup: Ruby 2, Unicorn, New Relic, exception tracking, Sendgrid etc...
Merge remote-tracking branch 'upstream/master'

* upstream/master: (112 commits)
  Update SECURITY.md
  initial draft of security document
  remove email footer font override
  SECURITY: correct our CSRF implementation to be much more aggressive
  distributed memoizer added to ensure absolute duplicate posts don't get through
  mock redis for mock redis goodness
  don't ever delete unprocessable emails
  FIX: Loading was broken on activity streams
  FIX: Allow clicks on @names
  Fix auto-group refresh response so that ajax callback runs
  hide groups nav link from non-admins
  correct email styles
  FIX: Can click on your own links again
  Some tests for the user stream
  Minor fixes. Link directoy to user activity to avoid a redirect.
  Moved highestSeenByTopic to the Discourse.Session
  Moved Discourse.ajax into a mixin.
  Moved Resolver to new File
  Remove Discourse.transient. Use a singleton for session data, it's a lot cleaner.
  Upgrade Ember to Fix CVE-2013-4170
  ...
Merge w/ upstream
Add puma