fix bug: 多次重试Http交互时，上一次的残留事件 干扰了本次的事件流转
BlobReactor & SignalReactor 接口方法修改：onTransactionFinished =>
onTransactionFailure，该方法只在接收 数据失败时 被调用。示意图如下：
                    +---->  onBlobReceived/onResponseReceived (succeed)
+-----+             |
|start|--> process -+
+-----+             |
                    +----> onTransactionFailure (failed)