Second AS2.0 javascript lib

FYI: Nick Jennings works on alternative implementation of AS2.0 in
javascript. He uses it in rewrite of 'polyglot' server
http://sockethub.org/ heavily using ActivityStreams

more details in:
https://lists.w3.org/Archives/Public/public-rdfjs/2015Mar/0009.html

code:
https://github.com/silverbucket/activity-streams.js

I also just added it to:
https://www.w3.org/wiki/Socialwg#Implementations