catch all exceptions while sending data through WebSocketServer

Signed-off-by: Manson Li <manson.li@matchstick.tv>
disconnect session before stopping application

Signed-off-by: Manson Li <manson.li@matchstick.tv>
donot check 'appInfo' when received command 'join'

Signed-off-by: Manson Li <manson.li@matchstick.tv>
add Platform Abstract Layer Protocol

Signed-off-by: Manson Li <manson.li@matchstick.tv>