Rather than having a shield subfolder, what do you think of flipping it around? Go stdlib and a few other places have a `cmd` folder.

so `github.com/badges/buckler/cmd/buckler` is the folder containing the buckler CLI.
so we could make `github.com/badges/buckler` the library import (stdlib actually has a pkg/ subfolder as well, but meh).

Also, let's just call this buckler (not shield).