Add percentages to Metrics.

src/de/tudarmstadt/maki/simonstrator/api/common/metric/Metric.java

@@ -50,7 +50,7 @@ public interface Metric<M extends MetricValue<?>> {
 	 */
 	public enum MetricUnit {
 		NONE(""), TRAFFIC("byte/s"), TIME("us"), DATA(
-				"byte"), UNKNOWN("unknown"), JOULE("J"), METER("m");
+				"byte"), UNKNOWN("unknown"), JOULE("J"), METER("m"), PERCENTAGE("%");
 
 		private final String representation;