Add no-link option for non-buck projects / submodule alternative

[nikhedonia]

Buckaroo's resolution process flattens the dependency graph, places installed packages in the buckaroo folder and wires up all .buckconfig files.

The resolution process makes Buckaroo quite useful for non-buck(aroo) projects as it avoids many issues that git-submodules have.

Let's implement a no-link option that skips all buckconfig related operations.

Q: What would the best syntax be?