Run govuk_update_mirror as an upstart task
Run govuk_update_mirror as an upstart task

By running the govuk_update_mirror script as an upstart task, we can
register other tasks to run when it's finished. I plan to use this to
cause the upload task to run when the mirror task finishes.

alphagov/govuk-puppet,alphagov/govuk-puppet,alphagov/govuk-puppet,alphagov/govuk-puppet,alphagov/govuk-puppet,alphagov/govuk-puppet