content sorting enhances

prepend sorting of contents by `ref_no`
Merge pull request #98 from bitzesty/content-sorting-enhances

content sorting enhances
Merge branch 'master' of github.com:alphagov/content-planner
upgrade rails to 4.0.12

addresses [CVE-2014-7829](https://groups.google.com/forum/#!topic/rubyonrails-security/rMTQy4oRCGk)