add rules checking to configtest

src/main/java/org/graylog2/Main.java

@@ -98,8 +98,12 @@ public static void main(String[] args) {
             System.exit(1);
         }
 
-        // If we only want to check our configuration, we can gracefully exit here
+        // If we only want to check our configuration, we just initialize the rules engine to check if the rules compile
         if (commandLineArguments.isConfigTest()) {
+            GraylogServer server = new GraylogServer();
+            DroolsInitializer drools = new DroolsInitializer(server, configuration);
+            drools.initialize();
+            // rules have been checked, exit gracefully
             System.exit(0);
         }