set system properties to prevent OSVersion parse error

Author: simongruenbacher

web-image/src/com.oracle.svm.webimage/src/com/oracle/svm/webimage/WebImageSystemPropertiesSupport.java

@@ -57,12 +57,12 @@ protected String javaIoTmpdirValue() {
 
     @Override
     protected String osNameValue() {
-        return "Unknown";
+        return "Web Image";
     }
 
     @Override
     protected String osVersionValue() {
-        return "Unknown";
+        return "0.0";
     }
 
 }