- add externUserID and meetingID attributes from join API

bigbluebutton-client/src/ViewersModule.mxml

...ient/src/org/bigbluebutton/main/model/BbbModuleManager.as

.../bigbluebutton/modules/viewers/ViewersEndpointMediator.as

...c/org/bigbluebutton/modules/viewers/model/ViewersProxy.as

...ebutton/modules/viewers/model/services/IViewersService.as

...gbluebutton/modules/viewers/model/services/JoinService.as

...n/modules/viewers/model/services/NetConnectionDelegate.as

...button/modules/viewers/model/services/ViewersSOService.as