[CHEF-5056] Update Rails to 3.2.17

Addresses these CVEs:

* https://groups.google.com/forum/#!topic/rubyonrails-security/tfp6gZCtzr4
* https://groups.google.com/forum/#!topic/rubyonrails-security/LMxO_3_eCuc
Merge pull request #26 from smith/nls/CHEF-5056-rails-update

[CHEF-5056] Update Rails to 3.2.17