Add support for sfpkg generation

[GitTorre]

This is not high priority, as discussed. However, it would be great to have parity among the various client impls in this regard - deployment packaging and uploading. The file/folder structure used today here is correct. The only thing left to do is to add support for sfpkg file generation, where the code/data/config folder structure (zipped or not) + configuration files are housed in a single sfpkg file (which is also a zip file...).