js port + gist api

This is ported to my branch of cohttp so the APIs are a little bit out of kilter with what will be released.  So not for merging just yet.

Javascript compilation enabled and tested.

Includes an almost complete gist API (only missing "is gist starred" I think).  Full gist API test available here (requires an access token generated with git-jar);

http://andrewray.github.io/iocamljs/github.html