Add check and in operations for this Tracker resource

[crstamps2]

I am reopening issue #16 as I think I have a legit use case for this now. Basically here is the flow.

I have created a PR on some repo, and that repo has status checks set. One of them happens to be that the story has been accepted. With Tracker's activity hooks and with the ability to have webhooks on resources now, I could take the activity webhook and report the status of the story back to the PR.

I started to go down the route of using the RSS feed, but the tracker feed is pretty unusable. I thought this would be a cleaner way. Doing some parsing on the incoming hook would be pretty easy.