Remove "IE hack" from Liquibase XML.

The "IE hack" is the extra space in front of the /> in an empty tag.
I'm removing it because when REXML write documents it doesn't place it
in there and I don't want the first changeset added automatically by
buildr to result in a noisy diff.
Manage Liquibase changeset files with Buildr.
Add initial Liquibase script.

Also reconcile values in Hibernate annotations with Liquibase script.
Generalized database setup in deploy scripts.

Also get Gutterball running Liquibase during deployment.
Update README with information on liquibase task.
Remove old gen-db-update.py and default to changelog.xml.
Allow configurable liquibase file prefix.