Move package root to subdirectory

[edvald]

I found out the hard way that lerna doesn't really support having a package in the repo root. I figure we'll also have multiple packages in the repo at some point, so I'm thinking we should move all the stuff we end up packaging and releasing as garden-cli to a garden-cli subdirectory.

We'd keep some stuff like bin, docs and some config stuff in the root. Figure it'd also make the top-level directory a bit cleaner, it's a bit crowded at this point.

Any objections...?

[thsig]

Sounds good to me.