5416 checksum attribute

4963 import cron should abort old imports

4758 cron job to finalise compliance check set validations  

* The factory already creates `StopPoint`s for us, so we don't need to
  create any additional ones in the test. Previously this would give us
  eight stop points instead of three or five.
* Update the checksum in the factory after generating stop points. We
  need to do this because otherwise the checksum will be incorrect, not
  taking into account the new stop points. Without this change, the
  checksum starts out in an inconsistent state and causes the:

      1) Chouette::Route checksum behaves like checksum support doesn't change the checksum on save if the source hasn't been changed
         Failure/Error: expect(subject.checksum).to eq(checksum)

           expected: "bc0e7b37243682904bd7013108258fdc744b03e0c59ed1a30e24e112a49242c1"
                got: "b39d643fdd4f9d6ff62547750508af728a187de29a3d6e4295f9bb3d13559a51"

           (compared using ==)
         Shared Example Group: "checksum support" called from ./spec/models/chouette/route/route_base_spec.rb:5
         # ./spec/support/checksum_support.rb:84:in `block (2 levels) in <top (required)>'

  test to fail.

Refs #5416

Copy over the `Import.abort_old` method to this class. For now I haven't
bothered with moving it to a consolidated module. We'll see, maybe
that's a better approach. For now I'm going with a relaxed copy-paste
solution until we decide that the increased complexity of the module is
worth the deduplication.

We need this method to be able to abort stale imports. We'll be doing
this, similarly to imports, in a regular cron job.

Refs #4758

Refs #5416

Refs #5416

Refs #5416