Customization for virtio.iso

[MarcoSuhr]

First of all, I like that feature a lot. Automatically pulling the newest version of virtio is really helpful.
I would love to see an improvement in form of customization.

Let the user decide the location. /var/lib/vz/iso as the default is okay, but it would be better if the user could chose a storage to their liking - f.e. an SMB/NFS share for ISO files.
It's not rare PVE is installed on a USB-Stick (especially for test-environments) and therefore the space might be limited.

I made the changes already for myself but I think more people would benefit from those changes.

[thorstenspille]

Hi Marco,
sometimes there are Problems with the download bandwidth of the virtio-win iso from the fedorapeople server, so I moved the downloader to the bashclub apt repo. Currently the ISO is in the static path /var/lib/vz/template/iso.