初步的网页国际化支持

1. 添加 jquery i18n js 依赖和入口
2. 在登录界面添加语言切换功能

web/share/i18n/i18n_cn.json

@@ -0,0 +1,10 @@
+{
+    "username": "用户名： ",
+    "password": "密码： ",
+    "2fa_code": "2FA 验证码： ",
+    "if_enabled": "如果有",
+    "login": "登录",
+    "select_language": "选择语言： ",
+    "chinese": "简体中文",
+    "english": "英语"
+}

web/share/i18n/i18n_en.json

@@ -0,0 +1,10 @@
+{
+    "username": "Username: ",
+    "password": "Password: ",
+    "2fa_code": "2FA code: ",
+    "if_enabled": "if enabled",
+    "login": "Login",
+    "select_language": "Select language: ",
+    "chinese": "Simplified Chinese",
+    "english": "English"
+}