Add constructors to allow use without requiring CDI

The KIE workbench editors being hosted in Eclipse will require a Data Model Oracle (DMO) which is comprised of all the resources contained in a project, compiled into an in-memory representation. The KIE workbench relies on CDI to inject various beans into the DMO, but dependency injection is not available in an Eclipse plug-in environment (I've spent several days trying to get Weld running in Eclipse without success). Therefore, constructors for all of the necessary beans must be exposed to allow "manual" construction.