Add cargo tree output

[abasu2]

I think it would be helpful to have access to the full dependency graph of any crate as part of the logging functionality of cargo sherlock. cargo tree displays the full dependency graph of a package given a Cargo.toml file; could we incorporate cargo tree into cargo sherlock?

[muhammad-hassnain]

That's a good idea, I will add the feature. Currently we do fetch the whole dependency tree for a crate, but just the top layer is returned.