Fix loading of non startable gamemodes

Signed-off-by: Lixfel <agga-games@gmx.de>

src/de/steamwar/bungeecore/ArenaMode.java

@@ -48,7 +48,8 @@ public class ArenaMode {
                 throw new SecurityException("Could not load SchematicTypes", e);
             }
 
-            new ArenaMode(configFile.getName().replace(".yml", ""), config);
+            if(config.contains("Server"))
+                new ArenaMode(configFile.getName().replace(".yml", ""), config);
         }
     }