Try redownloading files if they can't be decompressed

[nchaimov]

If decompression of a source archive fails, TAU Commander currently gives up and leaves the corrupt file behind. If decompression fails, it should instead try again in case the problem was transient, and fall through to later mirrors. If decompression fails, the corrupt file should be deleted before TAU Commander exits.

[nchaimov]

I think this would also fix #412