Corrupt jars files following SocketTimeoutException

[tombentley]

If a SocketTimeoutException occurs when downloading a jar from a remote repo it seems that the partially transferred file is left of the filesystem. On a subsequent run things break because the zip file is invalid.

[tombentley]

Maybe we should write to a foo-1.0.0.jar.part file and rename it when the download is complete. That would also allow us to resume a transfer using a range request.

[FroMage]

Fixed. We'll implement partial files and resuming later, it's not a priority since most files are small, and I expect we'll need parallel downloads too later.