Add Initiative

[daviegourevitch]

Hey, guys

I finished initiative. Took a little longer than expected, had some problems with falsy 0s.

Everything is working well. I'm gonna test it more but all normal use cases are covered.

Things still todo:

• Use the verbose function more. It isn't used much at the moment
• Limit the maximum number of dice someone can roll
• Tidy up the printed results, based on however people like it

I'd appreciate a merge, thanks!

[daviegourevitch]

Also note that I print my ID when there is an error so that people can let me know, so I can fix it. Also will be good for getting comments, etc