DTGOV-134 Workflow/KIE JAR: Add support for maven keywords - LATEST / RE...

https://issues.jboss.org/browse/DTGOV-134
If workflowVersion is null, throw an exception with a message like:  "DTGov workflow KIE jar could not be found in the S-RAMP repository."

For bonus points include the groupId, artifactId, and version info in the error message.