LINT: Adding scripts directory to lint, and fixing flake issues on them (#18949)
- [X] closes #18949
- [ ] tests added / passed
- [X] passes `git diff upstream/master -u -- "*.py" | flake8 --diff`
- [ ] whatsnew entry

Hello @datapythonista! Thanks for updating the PR.









Cheers ! There are no PEP8 issues in this Pull Request. :beers: 

##### Comment last updated on January 23, 2018 at 11:46 Hours UTC @gfyoung, thanks for your comments, fixed them.

I agree about documenting the scripts, but as you suggest I also think that should go in a separate PR. I think scripts like `find_commits_touching_func.py` are not being used, and I'm not sure if they're still useful.

Also, I'm thinking in merging `find_undoc_args.py` and `api_rst_coverage.py` in a single general script that checks all problems related documentation at once.

And there are others like the ones related to the release, that I'm surely not the best person to describe how to use them. :) thanks @datapythonista 

also if you can create an issue for https://github.com/pandas-dev/pandas/pull/19344#issuecomment-359865305 comments and change ``%`` to ``.format()`` in scripts would be great. (PR even better!)