Remove tooling related to creating releases

[pekkaklarck]

Different projects have different needs related to creating releases:

• Are wheels needed?
• Do universal wheels work?
• Is there a need to test packages locally?

Supporting these all with invoke tasks is possible but certainly not trivial. Instead of that, it's better to just add these standard commands to BUILD.rst and fine-tune them accordingly:

python setup.py sdist [bdist_wheel [--universal]]
twine upload dist/*