fix (#542): validate ignore-from-file in validate_rule_conf

[ndrwnaguib]

Fix #542. The ignore-from-file key wasn't validated in validate_rule_conf.

[coveralls]

coverage: 99.397% (+0.001%) from 99.396%
when pulling 36007a2 on ndrwnaguib:fix/issues-542
into 1f79e62 on adrienverge:master.

[adrienverge]

Thanks for tackling this @ndrwnaguib!

It looks good, please see my comments. Also:

• Could you use the same code style as the rest of the code? (this project doesn't use the Black format)
• This needs a test to make sure the problem won't come back. Can you update IgnoreConfigTestCase.test_run_with_ignored_from_file() to include a rule-scoped ignore-from-file like done in the ignore case?

[ndrwnaguib]

@adrienverge I rebased onto master using GitHub's update branch button. But, I checked the commit history, I do not see any merge commits, would you like me to drop it and rebase interactively instead?--unless you are going to squash the commits.

[adrienverge]

Hello,

I allowed myself to force-push to your branch because 2 of my requests were not addressed.

Also the commit title referenced #524 which is unrelated. I amended that and reworded the commit for better understanding and maintenance.

Let's merge now.

[ndrwnaguib]

I allowed myself to force-push to your branch because 2 of my requests were not addressed.

That's alright. Sorry about missing them.

Also the commit title referenced #524 which is unrelated. I amended that and reworded the commit for better understanding and maintenance.

Thank you. I meant #542.