Improve Chinese (Simplified) Translations (#6024)

* i18n: (zh-CN) Change `工作人员` (staff) to `管理人员`
Suggested by @Gargron at https://github.com/tootsuite/mastodon/pull/6005#discussion_r156678109

* i18n: (zh-CN) Change `协管` to `监察员`

* i18n: (zh-CN) Fix all "Are you" questions

* i18n: (zh-CN) Various improvements

* i18n: (zh-CN) Final clean-up

* i18n: (zh-CN) Change translation for 500

* i18n: (zh-CN) Remove spaces between time distances

* i18n: (zh-CN) Improve translations

config/locales/doorkeeper.zh-CN.yml

@@ -114,6 +114,6 @@ zh-CN:
       application:
         title: 需要 OAuth 认证
     scopes:
-      follow: 关注（或取消关注）、屏蔽（或取消屏蔽）用户
+      follow: 关注或屏蔽用户
       read: 读取你的帐户数据
       write: 为你发表嘟文