Update rails to 3.2.11

This patches severe security vulnerabilities. See:
http://weblog.rubyonrails.org/2013/1/8/Rails-3-2-11-3-1-10-3-0-19-and-2-3-15-have-been-released/

Proof-of-concept remote code execution will be published in a matter of hours:
https://twitter.com/hdmoore/status/289189534665678849