For resumable_download, fix #28 so that when tmp file is deleted, we …

[yami]

…delete the record; set connection pool size correctly; close connections for APIs which do not read body.

[coveralls]

Coverage increased (+0.01%) to 98.059% when pulling 65ea1f6 on con-multipart into 4b1456e on master.

[coveralls]

Coverage increased (+0.009%) to 98.055% when pulling 6e0938d on con-multipart into 4b1456e on master.

[coveralls]

Coverage increased (+0.004%) to 98.05% when pulling 2cc9804 on con-multipart into 4b1456e on master.

[rockuw]

其他情况也有需要删除record的吗？比如source object发生了变化。

[coveralls]

Coverage increased (+0.004%) to 98.05% when pulling 2cc9804 on con-multipart into 4b1456e on master.

[yami]

source object变化的场景已经cover了。

[rockuw]

如果temp文件存在，但是其中的内容已经被改变了呢？

[yami]

这个暂时没有cover，也不期望用户这样做。用户也完全可以修改record之类的。

[rockuw]

+1

[coveralls]

Coverage decreased (-0.05%) to 97.993% when pulling 2cc9804 on con-multipart into 4b1456e on master.