refactor: outsourced code in String function

src/main/java/org/bitbiome/commands/QuitCommand.java

@@ -6,7 +6,11 @@ public class QuitCommand implements CommandAPI {
 
     @Override
     public void performCommand(Scanner scanner, boolean isRunning, String message) {
-        System.out.println("You quitted!");
+        System.out.println(getQuitMessage());
         System.exit(0);
     }
+
+    public static String getQuitMessage() {
+        return "You quitted!";
+    }
 }