remove unused ref
remove unused ref

danmarshall/BotFramework-WebChat,billba/BotFramework-WebChat,billba/BotFramework-WebChat,billba/botchat,eanders-MS/BotFramework-WebChat,danmarshall/BotFramework-WebChat,eanders-MS/BotFramework-WebChat,danmarshall/BotFramework-WebChat,billba/botchat,billba/botchat,eanders-MS/BotFramework-WebChat,billba/BotFramework-WebChat