Look for per-project configuration file in parent directories

[chutzimir]

Inspired be ESLint's search, it looks for configuration files in all parent directories up until it reaches the user's home or root.

closes #571

[adrienverge]

Hello, thanks for this idea and implementation!

Although I'm favorable to the idea, this is a breaking change (behavior would start changing if top-level .yamllint files would be taken into account). Is anyone following this repo opposed to this?

Can you also add a test_multiple_parent_config_file() that checks that if multiple config files have conflicting rules options, the closest one takes precedence?

[coveralls]

Coverage: 99.392% (+0.006%) from 99.386% when pulling 80c1daa on chutzimir:parent-dir-config into 019c87d on adrienverge:master.

[coveralls]

Coverage: 99.31% (-0.08%) from 99.386% when pulling 584ae2c on chutzimir:parent-dir-config into 019c87d on adrienverge:master.

[chutzimir]

I addressed all of the above comments, so let me mark them as resolved. I just now noticed the CONTRIBUTING.md file, so I also fixed the linting problems per flake8 advice. I squashed the commits too, to keep the git history clean.

As to whether this is a breaking change or not... I understand your sentiment. I just want to note that I found it very counterintuitive to get different behavior when I edit a file depending on which directory I start from.

[adrienverge]

Thanks for the updated version @chutzimir, it looks good. Please see my 2 comments.

Since no one seems to be opposed to this feature (which is a breaking change), I'm +1 to merge it.

[adrienverge]

Great! Thanks for contributing to yamllint Georgi 👍