Pin pylint to 2.2.2 and fix numpy-related lint

[leouieda]

Pylint has started complaining about numpy imports. Disable these checks
and add numpy to their whitelist. Pin the pylint version so that this
type of errors doesn't creep up on new PRs and we upgrade pylint only
when we want to.

Reminders

• Run make format and make check to make sure the code follows the style guide.
• Add tests for new features or tests that would have caught the bug that you're fixing.
• Add new public functions/methods/classes to doc/api/index.rst.
• Write detailed docstrings for all functions/methods.
• If adding new functionality, add an example to the docstring, gallery, and/or tutorials.