Added support for multiple issue IDs using commas ( #6 )

The getArgument didn't quite work as I needed it to. What I expected for it was that it would split the arguments string like I did and just return me what I wanted. I tried to stick to the original syntax and comment the parts that needed it and if you want I will put more comments but as a lot of the code didn't have comments I didn't want to overcomment something as simple as this.