Bump i18n and backport CVE-2013-4491

* Bump i18n to 0.6.x to fix errors from travis
* Back port [CVE patch from 3-1](https://github.com/rails/rails/commit/31cfb3c71371f1aab106d83f689a9682bcee3eab) which fixes errors caused by upgrading to 0.6 + makes us safe.

Profit :moneybag: 

/cc @tamird