按暂停后有不短的延迟时间，过段时间后状态才改变

``` java
12-08 04:27:09.917 3669-3669/com.aspsine.multithreaddownload I/DownloadService: onStart()
12-08 04:27:09.917 3669-3669/com.aspsine.multithreaddownload I/DownloadService: onConnecting()
12-08 04:27:09.917 3669-3669/com.aspsine.multithreaddownload D/TEST: status=1
12-08 04:27:10.077 3669-3669/com.aspsine.multithreaddownload I/DownloadService: onConnected()
12-08 04:27:10.685 3669-3669/com.aspsine.multithreaddownload I/DownloadService: onProgress()
12-08 04:27:10.685 3669-3669/com.aspsine.multithreaddownload D/TEST: status=3
12-08 04:27:11.185 3669-3669/com.aspsine.multithreaddownload I/DownloadService: onProgress()
12-08 04:27:11.201 3669-3669/com.aspsine.multithreaddownload D/TEST: status=3
```

``` java
12-08 04:27:18.849 3669-3669/com.aspsine.multithreaddownload I/DownloadService: onDownloadPaused()
12-08 04:27:18.849 3669-3669/com.aspsine.multithreaddownload D/TEST: status=4
12-08 04:27:18.849 3669-3669/com.aspsine.multithreaddownload D/TEST: paused
12-08 04:27:18.849 3669-3669/com.aspsine.multithreaddownload D/TEST: paused updated
```

运行的是up的Demo，在Genymotion免费版上测试的，看log差不多是7秒左右。

猜想应该是硬件问题，然后在MX2上测试，情况良好，不过有时候也会，大概是2秒左右。

程序写的很棒，希望@Aspsine 能继续优化改进，谢谢。