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
display typeahead headers
separated out the dataset view in css and support multi-line titles better
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