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/java/fr/xephi/authme/message/MessageKey.java

@@ -167,12 +167,18 @@ public enum MessageKey {
     /** Email address successfully added to your account! */
     EMAIL_ADDED_SUCCESS("email.added"),
 
+    /** Adding email was not allowed */
+    EMAIL_ADD_NOT_ALLOWED("email.add_not_allowed"),
+
     /** Please confirm your email address! */
     CONFIRM_EMAIL_MESSAGE("email.request_confirmation"),
 
     /** Email address changed correctly! */
     EMAIL_CHANGED_SUCCESS("email.changed"),
 
+    /** Changing email was not allowed */
+    EMAIL_CHANGE_NOT_ALLOWED("email.change_not_allowed"),
+
     /** Your current email address is: %email */
     EMAIL_SHOW("email.email_show", "%email"),