Add task to fix invalid documents
Add task to fix invalid documents

This commit adds a temporary rake task that fixes an invalid document
introduced by a Whitehall bug.

There are documents with `content_id:
"5fe3cc51-7631-11e4-a3cb-005056011aef"`. There is an `:en` version and a
`:cy` version. Due to the Whitehall issue the last edition on the `:cy`
version has an incorrect `base_path` (no `.cy`).

The issue has caused another document to be created `content_id:
"a8364f44-3f21-43e5-8351-d150fb177649"`. The presence of this document
is preventing Whitehall from updating the correct one.

The task deletes the erroneously created document then updates the
`base_path` of the most recent edition of the otherwise valid document
to correctly reflect its locale.

Once this has been run the document will be republished from Whitehall.

alphagov/publishing-api,alphagov/publishing-api