Make test more complete
Pull out file upload quarantine simulation

Pulling this out allows us to use it outside of cucumber features so
we can have tests that behave closer to what happens on production.
Stop validations failing on image data re-use

Classfication featurings are copied onto newly drafted editions but
because of the way file upload quarantining works, the file is not
where carrierwave expects it to be, causing the "presence" check on
the file to fail in the ClassificationFeaturingImageData model. The
end result is that any copied ClassificationFeaturings will not be
valid (and thus will not save), causing the new edition to lose any
featurings on topical events it may have had. By only validating the
file when it changes (i.e. when it's created or when the a new file is
uploaded), classification featurings will be correctly persisted
across newly drafted editions.
Merge pull request #527 from alphagov/revising-editions-loses-topical-featurings

Revising editions loses topical featurings

https://www.pivotaltracker.com/story/show/48500995