Use jbuilder gem for json generation
Different representations of anon feedback JSON

Clients can handle different feedback based on the 'type' attribute.
Add missing spec for anon long-form feedback
Add the user-agent info to the FeedEx JSON feed

This is done to allow analysts to slice and dice feedback by OS/browser/browser version.
Add id to the Feedex JSON feeds

Right now, there isn't a way to 'freeze' the Feedex results to a certain
point in time. This causes problems when paginating over the results.

The long-term solution to this problem is to add a 'before' parameter
that's added to subsequent page links; however adding the record
'id' will allow to de-dupe records on the client-side if page-shift occurs.
Merge pull request #183 from alphagov/add-user-agent-and-id-to-feedex-json

Add user agent and id to the Feedex JSON results