Update Locale zh-HK (#2818)

* locale: Add missing translation in zh-HK.yml

* locale: fix consistancy in zh-HK.yml translation

* locale: Improve zh-HK yml translations

* Use "PuSH" in all "PubSubHubBub" occurances.
* Simplify text on front page.
* Improve doorkeeper authorization table translations.
* Simplify setting form text for better layout.
* Improve "Business Email" translation.

* locale: Update zh-HK.json

* Fix untranslated text.
* Improve translations.

config/locales/doorkeeper.zh-HK.yml

@@ -65,7 +65,7 @@ zh-HK:
         revoke: 是否確定要取消授權？
       index:
         application: 應用程式
-        created_at: 授權於
+        created_at: 授權日期
         date_format: "%Y-%m-%d %H:%M:%S"
         scopes: 權限範圍
         title: 已獲你授權的程用程式