Add RamUsage to be safe

BauSystem_Main/src/de/steamwar/bausystem/RamUsage.java

@@ -23,6 +23,10 @@ import java.lang.management.ManagementFactory;
 
 public class RamUsage {
 
+    private RamUsage() {
+        throw new IllegalStateException("Utility Class")
+    }
+
     public static double getUsage() {
         try {
             long memorySize = ((com.sun.management.OperatingSystemMXBean) ManagementFactory.getOperatingSystemMXBean()).getTotalPhysicalMemorySize();