Cleaner handling of tmp files in Web Interface

[rdmark]

The 'download_to_iso' method in the Web Interface currently manually creates tmp files under /tmp and does not clean them up afterwards. Also, when unzipping a tmp file, we store the resulting files into /tmp as well.

Some ideas include: Using the python tempfile library. Piping the python file-like object to unzip or genisoimage. Piping the output of unzip into genisoimage.

See https://github.com/akuker/RASCSI/pull/525 for previous discussion.