Added emailChange listener to API

conference.js

             }
         );
 
-        APP.UI.addListener(UIEvents.EMAIL_CHANGED, this.changeLocalEmail);
+        APP.UI.addListener(UIEvents.EMAIL_CHANGED,
+            this.changeLocalEmail.bind(this));
         room.addCommandListener(this.commands.defaults.EMAIL, (data, from) => {
             APP.store.dispatch(participantUpdated({
                 conference: room,
         APP.store.dispatch(updateSettings({
             email: formattedEmail
         }));
-
+        APP.API.notifyEmailChanged(localId, {
+            email: formattedEmail
+        });
         sendData(commands.EMAIL, formattedEmail);
     },
 

doc/api.md

 }
 ```
 
+* **emailChange** - event notifications about email
+changes. The listener will receive an object with the following structure:
+```javascript
+{
+"id": id, // the id of the participant that changed his email
+"email": email // the new email
+}
+```
+
 * **participantJoined** - event notifications about new participants who join the room. The listener will receive an object with the following structure:
 ```javascript
 {
 var displayName = api.getDisplayName(participantId);
 ```
 
+You can get the email of a participant in the conference with the following API function:
+```javascript
+var email = api.getEmail(participantId);
+```
+
 You can get the iframe HTML element where Jitsi Meet is loaded with the following API function:
 ```javascript
 var iframe = api.getIFrame();

modules/API/API.js

         });
     }
 
+    /**
+     * Notify external application (if API is enabled) that user changed their
+     * email.
+     *
+     * @param {string} id - User id.
+     * @param {string} email - The new email of the participant.
+     * @returns {void}
+     */
+    notifyEmailChanged(
+            id: string,
+            { email }: Object) {
+        this._sendEvent({
+            name: 'email-change',
+            email,
+            id
+        });
+    }
+
     /**
      * Notify external application (if API is enabled) that the conference has
      * been joined.

modules/API/external/external_api.js

     'audio-availability-changed': 'audioAvailabilityChanged',
     'audio-mute-status-changed': 'audioMuteStatusChanged',
     'display-name-change': 'displayNameChange',
+    'email-change': 'emailChange',
     'feedback-submitted': 'feedbackSubmitted',
     'incoming-message': 'incomingMessage',
     'outgoing-message': 'outgoingMessage',
                 }
                 break;
             }
+            case 'email-change': {
+                const user = this._participants[userID];
+
+                if (user) {
+                    user.email = data.email;
+                }
+                break;
+            }
             case 'avatar-changed': {
                 const user = this._participants[userID];
 
         return displayName;
     }
 
+    /**
+     * Returns the email of a participant.
+     *
+     * @param {string} participantId - The id of the participant.
+     * @returns {string} The email.
+     */
+    getEmail(participantId) {
+        const { email } = this._participants[participantId] || {};
+
+        return email;
+    }
+
     /**
      * Returns the formatted display name of a participant.
      *