Merge pull request #17 from theodi/master

pulling from master
Altering the certificate.lastest method to ensure that only published certificates are returned
Added 'can :read, Dataset' to CanCan
Adding feature to access datasets as atom feeds, through the route 'datasets/:id/to_atom' and xml_feed.rb
Changed route from 'to_atom' to 'atom.xml'
Added field to responses to store autocompletion messages
Simplified surveyor JS using a field state
Added new messages for autocomplete overriding
Added autocomplete override form and changed to display contextually
Fixed autocomplete check
Merge pull request #536 from Pavling/latest_certificate_method_tweaks

Tweaks to certificate.latest method
addressing issues raised on PR
including the route helpers in the xml_feed.rb file
Merge pull request #542 from The-Skas/feature/atom

Feature/atom
Added model to store autocomplete messages
Added checks for missing kitten data
Added validation check for an explanation message
Updated survey to store autocomplete override messages
Updated templates to show correct validation and styles for autocomplete override messages
Merge pull request #552 from theodi/external

Atom to production