Skate and charm/kv duplicate code

[toby]

Skate and the charm kv command are currently nearly copy and paste clones of each other. This makes it hard to keep them in sync and is generally not a great idea. We should make a module that has all of the Cobra CLI code in one place and use it for both skate and charm kv. It probably makes sense to have that be a submodule of Skate that gets imported in the main.go for Skate and Charm.