Updates to opsgenie hook

I'm playing around with some ideas for structuring the code.

I commented out the test for the unhandled case because I wasn't sure if that message was a valid one or if we would at least always have some of the other fields.

I'm not sure if this is better or worse than what is there, but I just noticed a couple things (like we could just use a map for the description to action mapping) that I wanted to play around with.