Refactor jBPM out of Drools core

Use the Assembler/Weaver mechanism to move jBPM out of drools core

other notes:

current impl exposes both drools-specific and jbpm-specific methods
core should not account for the underlying type: we'd rather give a wrapper or a common super-type instead of a different map for rules and processes.

aim for API like:

 kpg.get(Rules.class).getRules()