Use pre-commit hook with flake8 for contributors

[toti1212]

Hi there!
Do you think that adds a .pre-commit hook with flake8 can be useful for contributors?

[bitglue]

I personally don't like to conflate my git workflow with my testing cycle, so I run it manually or in tox.

Travis catches any issues that make it into a PR.

But if you would like to submit a configuration that makes it easier for people who do want to use pre-commit hooks to do so, without encumbering those who do not, that would be fine.

[daneah]

@toti1212 is the suggestion here to create, specifically, a hook definition for use with pre-commit? I think this would meet the criteria @bitglue suggests—users could use pyflakes as a pre-commit (the tool) hook, but would not be required to in any sense.

I'd be happy to submit such a pull request if that's amenable!