Great job! Was looking for this method in steem.js a few days ago. Nice to see it implemented now!

I have a few questions:
-What should I do with the weight parameter? Just set to 1?
-The perma link is the url of the post?
-Can we also use this method to upvote for comments? Or is that what you meant in the last sentense in your post and that is maybe coming up?
-Is there any documentation of the return data of the methods in the library? Probably JSON formatted... but how is the data organized?

Maybe all questions I can figure out myself by using the code.... but might save some people some time.

Again great job and looking forward to use this library! Probably in a few days , I hope ;-)!