fix true/false

src/main/java/ch/hevs/isi/core/BooleanDataPoint.java

@@ -26,7 +26,7 @@ public class BooleanDataPoint extends DataPoint{
         String s;
         s = this.getLabel();
         s += "=";
-        s += this.getValue();
+        s += this.getValue() ? "1" : "0";
         return s;
     }
 }