unpack should work when to doesn't exist or not specified

[zippy]

You shouldn't have to specify a to when unpacking or at least it should work if the directory doesn't exist, i.e. there should be default behavior. here are some options:

• use the name of the package file itself which shouldn't be bundle, but rather .json
• use snake cased version of the name, as the directory name,
• use the value of to as the directory name if that directory doesn't exist.

this would make unpack feel like the familiar git clone