Add support for different database targets to the command line installer for new installs

[natechadwick]

Currently the command line installer defaults to installing with the embedded apache derby database for new installs. We need to add an option to the installer to support targeting other supported database formats (MySQL, SQL Server, Oracle). For simplicity this could use a property file format like the rxconfig/Installer/rxrepository.properties and -Ddbprops= to specify the database target on the install command line.

NOTE: Upgrades handle the different databases ok, this is a limitation on the new install only.