Add pylint action with Google style configuration.

[lucasb-eyer]

This would run pylint with the official Google style configuration on every PR automatically, saving us quite a bit of time.

We can already see results of it in this PR

However, it seems that maybe we should submit the configuration here and fine-tune it a bit? I'm seeing several lint errors that we don't actually hit internally, for example:

So we should see if we like this difference, and/or where it comes from, before merging.

[andsteing]

I would propose to

1. reconfigure to exactly match issues that are also checked internally
2. fix all complaints internally
3. create PR from updated internal state
4. merge this PR