config.disableDesktopSharing - when set to false will disable desktop
sharing
interfaceConfig.DESKTOP_SHARING_BUTTON_DISABLED_TOOLTIP - when value is
assigned, will not hide the desktop sharing button completely, but show
as disabled with this value used as the tooltip text.
Audio only mode can be used to save bandwidth. In this mode local video is muted
and last N is set to 0, thus disabling all remote video.
When this mode is enabled avatars are shown.