Data migration to move shellfish guides

See: https://www.pivotaltracker.com/story/show/44075075

Note that this should be run just after this puppet pull request goes
live:

https://github.com/alphagov/puppet/pull/343
Merge pull request #221 from alphagov/shellfish-slug-renames

Data migration to move shellfish guides
Add Dari locale.
Revert "Upgrade to latest minitest."

This reverts commit a4f136dcaec906e8edae06bf313ec27f5d30044c.

We've noticed that the latest version of minitest prevents us from
running focussed (i.e. specified by name) tests. @edds has also
noticed that it's generating some warnings on CI. We're
downgrading until we have time to investigate further.
Dari is RTL.

I'm not sure how wise it is to hard-code the specific list in this test,
but lets get the build working.