feat(iframeAPI): implement avatar change commands

conference.js

                 'failed to create local tracks', options.devices, err);
             return Promise.reject(err);
         });
-    }
-
-/**
- * Changes the email for the local user
- * @param email {string} the new email
- */
-function changeLocalEmail(email = '') {
-    email = email.trim();
-
-    if (email === APP.settings.getEmail()) {
-        return;
-    }
-
-    APP.settings.setEmail(email);
-    APP.UI.setUserEmail(room.myUserId(), email);
-    sendData(commands.EMAIL, email);
 }
 
 /**
             APP.UI.initEtherpad(value);
         });
 
-        APP.UI.addListener(UIEvents.EMAIL_CHANGED, changeLocalEmail);
+        APP.UI.addListener(UIEvents.EMAIL_CHANGED, this.changeLocalEmail);
         room.addCommandListener(this.commands.defaults.EMAIL, (data, from) => {
             APP.UI.setUserEmail(from, data.value);
         });
             APP.API.notifyReadyToClose();
             maybeRedirectToWelcomePage(values[0]);
         });
+    },
+
+    /**
+     * Changes the email for the local user
+     * @param email {string} the new email
+     */
+    changeLocalEmail(email = '') {
+        email = email.trim();
+
+        if (email === APP.settings.getEmail()) {
+            return;
+        }
+
+        APP.settings.setEmail(email);
+        APP.UI.setUserEmail(room.myUserId(), email);
+        sendData(commands.EMAIL, email);
+    },
+
+    /**
+     * Changes the avatar url for the local user
+     * @param url {string} the new url
+     */
+    changeLocalAvatarUrl(url = '') {
+        url = url.trim();
+
+        if (url === APP.settings.getAvatarUrl()) {
+            return;
+        }
+
+        APP.settings.setAvatarUrl(url);
+        APP.UI.setUserAvatarUrl(room.myUserId(), url);
+        sendData(commands.AVATAR_URL, url);
     }
 };

doc/api.md

 
 You can send command to Jitsi Meet conference using ```executeCommand```.
 ```
-api.executeCommand(command, arguments)
+api.executeCommand(command, ...arguments)
 ```
 The ```command``` parameter is String object with the name of the command.
-The ```arguments``` parameter is array with the arguments required by the command.
-If no arguments are required by the command this parameter can be omitted or you can pass empty array.
 Currently we support the following commands:
 
 
 ```
 * **toggleAudio** - mutes / unmutes the audio for the local participant. No arguments are required.
 ```
-api.executeCommand('toggleAudio', [])
+api.executeCommand('toggleAudio')
 ```
 * **toggleVideo** - mutes / unmutes the video for the local participant. No arguments are required.
 ```
-api.executeCommand('toggleVideo', [])
+api.executeCommand('toggleVideo')
 ```
 * **toggleFilmStrip** - hides / shows the film strip. No arguments are required.
 ```
-api.executeCommand('filmStrip', [])
+api.executeCommand('filmStrip')
 ```
 * **toggleChat** - hides / shows the chat. No arguments are required.
 ```
-api.executeCommand('toggleChat', [])
+api.executeCommand('toggleChat')
 ```
 * **toggleContactList** - hides / shows the contact list. No arguments are required.
 ```
-api.executeCommand('toggleContactList', [])
+api.executeCommand('toggleContactList')
 ```
 
 * **toggleShareScreen** - starts / stops the screen sharing. No arguments are required.
 ```
-api.executeCommand('toggleShareScreen', [])
+api.executeCommand('toggleShareScreen')
 ```
 
 * **hangup** - Hangups the call. No arguments are required.
 ```
-api.executeCommand('hangup', [])
+api.executeCommand('hangup')
+```
+
+* **email** - Hangups the call. No arguments are required.
+```
+api.executeCommand('email', 'example@example.com')
+```
+
+* **avatarUrl** - Hangups the call. No arguments are required.
+```
+api.executeCommand('avatarUrl', 'avatarUrl')
 ```
 
 You can also execute multiple commands using the method ```executeCommands```.

modules/API/API.js

         "toggle-contact-list": APP.UI.toggleContactList,
         "toggle-share-screen":
             APP.conference.toggleScreenSharing.bind(APP.conference),
-        "video-hangup": () => APP.conference.hangup()
+        "video-hangup": () => APP.conference.hangup(),
+        "email": APP.conference.changeLocalEmail,
+        "avatar-url": APP.conference.changeLocalAvatarUrl
     };
     Object.keys(commands).forEach(function (key) {
-        postis.listen(key, commands[key]);
+        postis.listen(key, args => commands[key](...args));
     });
 }
 

modules/API/external/external_api.js

     "toggleChat": "toggle-chat",
     "toggleContactList": "toggle-contact-list",
     "toggleShareScreen": "toggle-share-screen",
-    "hangup": "video-hangup"
+    "hangup": "video-hangup",
+    "email": "email",
+    "avatarUrl": "avatar-url"
 };
 
 /**
  * @param name the name of the command
  * @param arguments array of arguments
  */
-JitsiMeetExternalAPI.prototype.executeCommand = function(name, argumentsList) {
+JitsiMeetExternalAPI.prototype.executeCommand
+= function(name, ...argumentsList) {
     if(!(name in commands)) {
         logger.error("Not supported command name.");
         return;
     }
-    var argumentsArray = argumentsList;
-    if (!argumentsArray)
-        argumentsArray = [];
-    sendMessage(this.postis, {method: commands[name], params: argumentsArray});
+    sendMessage(this.postis, {method: commands[name], params: argumentsList});
 };
 
 /**