Adds a progress bar.

With full decimal percentage display, this is both more responsive
and less noisy in using up screen real estate. Also, we can reuse the
progressbar in db:seeds rake task.
Adds page_id to be inserted in journals.

This is due to the not-null constraint on page_id in the wiki content
journals.
Treats nil changed_data gracefully.

It would fail rather hard previously.
Fixes missing sequence update.