Drools plugin tests rewritten to RedDeer

New version of tests for Drools plugin.
- written in RedDeer and rid of all the old dependencies
- tests for Drools 6.0 features
- tests are independent of each other
- more tests to come (not all were migrated yet, new ones keep coming)

Also includes RedDeer framework for Drools plugin.
- provides classes for basic work with Drools (preferences, wizards)
- more yet to come (editors, views)