Added EmailChangedEvent (#1549)

* Added EmailChangedEvent

* Fix failing tests

Silly.

* Documented the EmailChangedEvent

* Separate messages for cancelled email event

* Added lang todos for all the languages I can't speak

I wish I could though.

* Checkstyle satisfaction

* Changed log level to info for cancelled events

src/main/resources/messages/messages_zhtw.yml

@@ -101,6 +101,8 @@ email:
     send_failure: '&b【AuthMe】&4無法傳送電子郵件，請聯絡管理員.'
     change_password_expired: '&b【AuthMe】&6您現在不能使用這個指令變更密碼了.'
     email_cooldown_error: '&b【AuthMe】&c電子郵件已經寄出了. 您只能在 %time 後才能傳送.'
+    # TODO add_not_allowed: '&cAdding email was not allowed'
+    # TODO change_not_allowed: '&cChanging email was not allowed'
 
 # Password recovery by email
 recovery: