addComment API functionality

Hi there,

I have added the functionality to use the addComment API functionality that I've been using for a project of mine.

I have added the code for the jira.spec.coffee but I cannot figure out how to run the tests but manual testing indicates that it is working fine (yeah I know, "works on my machine" code)

More than happy to accept criticism and points on how/where to run the tests. Still a little new to NodeJS as well.

Thanks,

Steve