* Multi-db upgrade

Hello,

I did some development of your DBV program, have a look at my forked code and try it out.  I think you'll like it :)   It's been in production on my site for a few months, managing our 7 database revisions.

Improvements made:

* Multi-db upgrade
* DB credentials manager
* Run Selected Revision now works
* Edit revision via web UI

best regards,
Chris Fortune