[RFE] possibility to create my own base image

[pschiffe]

At first, I must say that I like upvm a lot, it's a great tool, thanks for that.

Now to the RFE, I'm thinking about this use case; I create new vm from base fedora 24, run updates there, install couple of packages and now, I would like to save that image and create a new vm from that saved image. And not only one, but as many as needed. I know that qcow2 supports copy on write, but the base image can't change after creating cow copy of that image. So, to achieve this, maybe valine should be able to create new cow image and upvm should be able to boot from it? Or something like that?