Update README.md
New version of README.md produced from task 'cake doc'
Adding autogeneration of README.md
Cakefile:
 - In the cake task 'doc', replace exec with execFile
 - Added -m option for my local build of docco

docs/PubSub.html
docs/docco.css
 - New versions of the documentation built with new 'cake doc' task.

src/PubSub.js
 - Removed some useless comments.