def push_single_account(account, message_type, message, params = {})
      params.merge!({
        account: account,
        message_type: message_type,
        message: message
        })
      self.send_request('push','single_account',params)
    end
def push_single_account(account, message_type, message, params = {})
      params.merge!({
        account: account,
        message_type: message_type,
        message: message
        })
      self.send_request('push','single_account',params)
    end
push消息（包括通知和透传消息）给单个账户或别名