newline-after-import with decorators

[lukekarrys]

This fixes the crash outlined in #592, when using a require statement inside a decorator.

While I was in there I also noticed that newline-after-import wasn't properly reporting if the next line was a decorator. I added this so it would be properly reported, but I can remove that if decorator support isn't something you want to add (I know it's still experimental).

[coveralls]

Coverage increased (+0.004%) to 97.651% when pulling 9e5627d on lukekarrys:592-newline-decorators into 2dec0a7 on benmosher:master.

[jfmengels]

@lukekarrys Awesome! Thanks a lot for this! Also thanks for the great report, which I did not have time to look at until now.

I'm not familiar with the decorators syntax, but this looks good to me.

As for supporting decorators... It's currently at stage 2, which is not the safest stage but means it will likely make it in the spec. I think the way this is implemented it should be fine even if it doesn't make it into the spec, or if it changes a bit. I'm fine with this at the moment. @benmosher?

[lukekarrys]

I rebased this against master and fixed a conflict in CHANGELOG.md. I can remove the changelog commit too if that's something that you normally do before releases.

[coveralls]

Coverage increased (+0.009%) to 94.904% when pulling 4e11e80 on lukekarrys:592-newline-decorators into 2cbd801 on benmosher:master.

[coveralls]

Coverage increased (+0.009%) to 94.904% when pulling 4e11e80 on lukekarrys:592-newline-decorators into 2cbd801 on benmosher:master.

[jfmengels]

I'm fine with this. @benmosher If you disagree supporting stage-2 features, that's fine by me too.

[benmosher]

Nope, I'm cool with decorators. Maybe not always all of stage 2, but definitely decorators. 😎