Consider supplementing getFile with downloadFile in VFS module

[benquarmby]

Currently the vfs.getFile method returns the body of a file as a raw argument. This is fine for small text files, but less optimal for binary files. It's also a different behavior to the dump and zip modules that pipe responses to a write stream.

I recommend adding a vfs.downloadFile method.

[itsananderson]

Would downloadFile return a stream, or would it take a file path and write the file directly to that path? I think having an API for both would be useful. Maybe readFile would give you a stream, downloadFile would take a path to write to, and getFile would work like it does today?

[benquarmby]

I think vfs.downloadFile should behave the same as dump.download and zip.download, which is to write to a specified file path. A readFile method that provides a stream makes sense too. Perhaps zip and dump should follow suit?