[feature] on-prem or bare metal configuration

[vielmetti]

It would be of interest to document the necessary bits to
make it possible to do an on-prem or bare metal version
of vhs, identifying all of the specific and particular
cloud dependencies and replacing them with self-hosted
versions of same.

So far, #2 (self-hosted storage with S3) looks like a start
at this, but beyond that, I'd appreciate any other dependencies
hiding here to see what the degree of difficulty might be.

[andrewhare]

Currently, you could use the stdout sink and pipe redirect you ouput to a file (for example), however we don't have a general-purpose file source yet so there's no way to read that data back into vhs. So in order for this to work we could add a file source and you could be free to stream the data to/from NAS or any other place you wanted to save the data.