Comment 7 for bug 445714

Scott Moser pointed out that he wants to use .tar.gz on the published images, because using the --sparse option of tar greatly reduces the size of the resulting file in comparison to plain gzip, so I went ahead and added support for .tar.gz on the image store proxy too, in addition to .gz.

This is all in release 1.0.3:

http://launchpad.net/image-store-proxy/1.0/1.0.3/+download/image-store-proxy-1.0.3.tar.gz

I've also added some logic to check that the hash used in the filename is indeed a hash, just for being pedantic. In practice, the image data must be signed by Canonical itself before getting to this point, so it should be safe no matter what.