Fixed error code of failed login.

app/assets/javascripts/app/lib/app_post/ajax.js.coffee

@@ -43,7 +43,7 @@ class _ajaxSingleton
       return if status is 0
 
       # do not show any error message on wrong login
-      return if status is 422
+      return if status is 401 && !settings.url.match('login')
 
       # do not show any error message with code 200
       return if status is 200

app/controllers/sessions_controller.rb

@@ -13,7 +13,7 @@ class SessionsController < ApplicationController
 
     # auth failed
     if !user
-      render :json => { :error => 'login failed' }, :status => :unprocessable_entity
+      render :json => { :error => 'login failed' }, :status => :unauthorized
       return
     end