Clarify plans/vision for Peril

Hi there!

I've recently discovered Peril having used Danger for some time and its a really nice project!

Reading [`VISION.md`](https://github.com/danger/peril/blob/master/VISION.md) helped me a lot to understand the background of the project but it left me wondering how the project will progress in future as it seems to be reasonably feature complete in that document.

Is it still planned for Peril to be run as a hosted service (similar to how [Hound](https://houndci.com) works)?

I know this is a volunteer run open source project and I am certainly not looking for an ETA but I would love to hear what the current plans are and if there is anything contributors can do to help accelerate the goal.