UP-4233 : Ant target for generating SQL schema update scripts

This adds the `ant` command:
 `db-gen-update-script`                   Generates the SQL files for a database upgrade.

It requires a parameter of what directory you want to dump the sql files.  3 files are generated, one for each database.  This utilizes the database connections setup in rdbm.properties.
Since this script is read-only as regards the target environment (generates the script to update the database, but doesn't actually update the database), should not depend upon `prodPrompt`, since no warning to the script executor is required (indeed, is not desirable, since the dire warning of `prodPrompt` is not true in this case.)