Upgrade to Rails 3.2.11 for security fixes

Jordan Hatch is disabling the vulnerable functionality here:
https://github.com/alphagov/alphagov-deployment/commit/b27aa94c4a36249614580f52f25f9f60d5283a49

See:
https://groups.google.com/forum/#!topic/rubyonrails-security/61bkgvnSGTQ/discussion
Merge pull request #47 from alphagov/bump_rails_to_3.2.11

Upgrade to Rails 3.2.11 for security fixes