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/events/EmailChangedEvent.java

@@ -0,0 +1,87 @@
+package fr.xephi.authme.events;
+
+import org.bukkit.entity.Player;
+import org.bukkit.event.Cancellable;
+import org.bukkit.event.Event;
+import org.bukkit.event.HandlerList;
+
+import javax.annotation.Nullable;
+
+/**
+ * This event is called when a player adds or changes his email address.
+ */
+public class EmailChangedEvent extends CustomEvent implements Cancellable {
+    private static final HandlerList handlers = new HandlerList();
+    private final Player player;
+    private final String oldEmail;
+    private final String newEmail;
+    private boolean isCancelled;
+
+    /**
+     * Constructor
+     *
+     * @param player The player that changed email
+     * @param oldEmail Old email player had on file. Can be null when user adds an email
+     * @param newEmail New email that player tries to set. In case of adding email, this will contain
+     *                the email is trying to set.
+     * @param isAsync should this event be called asynchronously?
+     */
+    public EmailChangedEvent(Player player, @Nullable String oldEmail, String newEmail, boolean isAsync) {
+        super(isAsync);
+        this.player = player;
+        this.oldEmail = oldEmail;
+        this.newEmail = newEmail;
+    }
+
+    @Override
+    public boolean isCancelled() {
+        return isCancelled;
+    }
+
+    /**
+     * Gets the player who changes the email
+     *
+     * @return The player who changed the email
+     */
+    public Player getPlayer() {
+        return player;
+    }
+
+    /**
+     * Gets the old email in case user tries to change existing email.
+     *
+     * @return old email stored on file. Can be null when user never had an email and adds a new one.
+     */
+    public @Nullable String getOldEmail() {
+        return this.oldEmail;
+    }
+
+    /**
+     * Gets the new email.
+     *
+     * @return the email user is trying to set. If user adds email and never had one before,
+     *        this is where such email can be found.
+     */
+    public String getNewEmail() {
+        return this.newEmail;
+    }
+
+    @Override
+    public void setCancelled(boolean cancelled) {
+        this.isCancelled = cancelled;
+    }
+
+    @Override
+    public HandlerList getHandlers() {
+        return handlers;
+    }
+
+    /**
+     * Return the list of handlers, equivalent to {@link #getHandlers()} and required by {@link Event}.
+     *
+     * @return The list of handlers
+     */
+    public static HandlerList getHandlerList() {
+        return handlers;
+    }
+}