Badge request: Kiln review

I would like to add support for badge that summarises the status of a [kiln review](http://help.fogcreek.com/8268/code-reviews-in-kiln).

Example badges:

Example url:
`https://img.shields.io/fogcreek/kiln/review/K12345.svg`

This would be using the [kiln review api 2.0](https://developers.fogbugz.com/default.asp?W209)

What I'm most unsure about is that because this is a service behind a paywall, I don't think I would be able to add service tests or live examples to the try.html. So I'm also a little unsure if shields accepts support for services like this.

I'm interested in submitting a pull request for this but just want to make this feature request is all good first.

Start by reviewing the Kiln Review API 2.0 documentation and the existing badge service patterns. Check try.html and determine how service tests or live examples can work for a paywalled service. Done means a Kiln review URL reports the requested statuses with the documented badge colors and has an agreed test strategy.

Written by the indexing model from the issue text.