Disable GetCpuUsage for now.

ATxCommon/SystemChecks.cs

@@ -38,6 +38,7 @@ namespace ATxCommon
         /// <returns>CPU usage in percent or -1 if an error occured.</returns>
         public static int GetCpuUsage() {
             // TODO: fix bug #36
+            return 0;
             try {
                 Log.Trace("Querying WMI for CPU load...");
                 var watch = Stopwatch.StartNew();