Upgrade Rails

Upgrades Rails to version 3.2.11 as per [this blog post](http://weblog.rubyonrails.org/2013/1/8/Rails-3-2-11-3-1-10-3-0-19-and-2-3-15-have-been-released/), including security fixes for CVE-2013-0156 & CVE-2013-0155