Fix plusplus regex so ++ relates only to adjacent word

(Moving https://github.com/github/hubot-scripts/issues/1191 to here.)

@patcon said:

> This doesn't seem right:
>
> https://www.evernote.com/shard/s27/sh/a7136918-6846-44b2-a54c-72c058991b1e/8e297e8ea6f8945333e12db75313b28f
>
> Likely culprit: https://github.com/github/hubot-scripts/blob/master/src/scripts/karma.coffee#L87
> cc: @arvinsingla
>
> EDIT: Just realized I'd mislabelled this as being an issue with karma.coffee, but it's plusplus.coffee
> cc: @ajacksified

@ajacksified said:

> the trouble is with names like "Herbert J. Hoover" - what's the adjacent word? I suppose we could try to allow a short list of punctuation (., spaces) but then how would you upvote "NOW! That's what I call music! 17"?
>
> I've found through experimenting with trying to be more clever about "word" detection can, in may cases, just make it difficult to upvote weird words. Thoughts?

@patcon said:

> Oh... maybe we could have an envvar for characters to ignore from matching, but default could be to allow spaces and whatever else you think should be in default? Like I think we only want single words (and our usernames are single words), but I'd rather not fork the script for that.
>
> Here's our use-case so far: People are often saying things like "hahaha that's totally whatever! erin++", and it used to take it as "hahaha++", but I think now its the whole sentence, if that makes sense. I'd love a way to customize for single-word plusplus'ing by default, but allowing multi-word if quotes are used. I can maybe figure out the regex for that later. coffeescript regex blocks allow easy interpolation, so I think we can figure out how to do a character blacklist :)