Introduce isLogin() for backwards compatibility with Plugins like

GuiRules (Fixes #705)

src/main/java/fr/xephi/authme/events/LoginEvent.java

@@ -30,6 +30,16 @@ public class LoginEvent extends CustomEvent {
         return player;
     }
 
+    /**
+     *
+     * @return
+     * @deprecated this will always return true because this event is only called if it was successful
+     */
+    @Deprecated
+    public boolean isLogin() {
+        return true;
+    }
+
     /**
      * Return the list of handlers, equivalent to {@link #getHandlers()} and required by {@link Event}.
      *