Update version number

Author: royleochan

src/main/java/seedu/address/MainApp.java

@@ -45,7 +45,7 @@
  */
 public class MainApp extends Application {
 
-    public static final Version VERSION = new Version(1, 2, 1, true);
+    public static final Version VERSION = new Version(1, 4, 0, true);
 
     private static final Logger logger = LogsCenter.getLogger(MainApp.class);