start DGRM plugin with cooja_default.config
start the DGRMconfigurator within the cooja_default.config instead of starting in DirectedGraphMedium.java
start DGRMVisualizerSkin in cooja_default.config now
instead of starting in DirectedGraphMedium
Merge pull request #449 from darki2002/cooja_default.config

Start DGRMConfigurator and DGRMVisualizerSkin in cooja_default.config