Add upstream exclusions to transitive dependencies

[AdamFrey]

This is a potential fix for https://github.com/RickMoynihan/lein-tools-deps/issues/66.

It works by explicitly listing all :exclusions from a dep's parents in the dependency tree to ensure that leiningen doesn't add a dependency during its own dependency resolution that should have been excluded.

I'll admit this is sort of inelegant so let me know if you have implementation opinions.

[RickMoynihan]

Thanks for this and the comprehensive example, I'll try and find some time to review.

[marco-m]

@RickMoynihan did you have a chance to review this PR ?