RuboCop lint rules, linting, TODO config added

[olleolleolle]

This PR adds a RuboCop configuration file with quite few excludes and such.

• lines in this projects are wider
• double quotes are double
• the features/ directory has code generated by Cucumber, so I excluded it

This all makes us compatible with chefstyle 0.6.0.

[olleolleolle]

Now, in order to reach "DCO" status, I'd need to re-do these commits.

Would a squash into a single commit be too dramatic? (Here, a single commit, with a DCO.)

[olleolleolle]

I filed this PR to rake, to get around the issue that it exposes its own .rubocop.yml in its downloaded files: ruby/rake#217

This is fixed here by us not including vendor/ in the scope of files to check.

[tas50]

@olleolleolle Any reason to not just use Chefstyle with the stock config like we're doing elsewhere?

[olleolleolle]

@tas50 Oh, I learned about Chefstyle while doing this change. But I failed to realize how much it takes care of.

(The first thing I did was to run rubocop, which failed, and so on. And, then incrementally, I took steps to make things work more and more. At the end, I saw that the Travis CI script (Rake default task) had a style task, so I began using that, even asking it to do "-a" for auto-correct.)

Gah.

So, can I close this with no change?

[olleolleolle]

Closing this with no change.