feat(DisplayName): Limit local and remote display name to 50 chars

conference.js

     CUSTOM_ROLE: "custom-role"
 };
 
+/**
+ * Max length of the display names. If we receive longer display name the
+ * additional chars are going to be cut.
+ */
+const MAX_DISPLAYNAME_LENGTH = 50;
+
 /**
  * Open Connection. When authentication failed it shows auth dialog.
  * @param roomName the room name to use
  * @param nickname {string} the new display name
  */
 function changeLocalDisplayName(nickname = '') {
-    nickname = nickname.trim();
+    const formattedNickname
+        = nickname.trim().substr(0, MAX_DISPLAYNAME_LENGTH);
 
-    if (nickname === APP.settings.getDisplayName()) {
+    if (formattedNickname === APP.settings.getDisplayName()) {
         return;
     }
 
-    APP.settings.setDisplayName(nickname);
-    room.setDisplayName(nickname);
-    APP.UI.changeDisplayName(APP.conference.getMyUserId(), nickname);
+    APP.settings.setDisplayName(formattedNickname);
+    room.setDisplayName(formattedNickname);
+    APP.UI.changeDisplayName(APP.conference.getMyUserId(), formattedNickname);
 }
 
 class ConferenceConnector {
         });
 
         room.on(ConferenceEvents.DISPLAY_NAME_CHANGED, (id, displayName) => {
-            APP.API.notifyDisplayNameChanged(id, displayName);
-            APP.UI.changeDisplayName(id, displayName);
+            const formattedDisplayName
+                = displayName.substr(0, MAX_DISPLAYNAME_LENGTH);
+            APP.API.notifyDisplayNameChanged(id, formattedDisplayName);
+            APP.UI.changeDisplayName(id, formattedDisplayName);
         });
 
         room.on(ConferenceEvents.PARTICIPANT_PROPERTY_CHANGED,