Multiple people have commented that having these two tools in one repository is confusing.
Let's separate them into two repositories.
This also will mean we can change the CLI (common) without library changes (rare) without running all the library tests (slow).
I think that the best way to do this is to publish DC/OS E2E to PyPI (see DCOS_OSS-3917).
We can also vendor DC/OS E2E inside a minidcos repository if that is opposed.