The `controller.go` is from: https://github.com/knative/serving/pull/1770, however, this adds 100% coverage of `controller.go`, which we have been missing in `knative/serving`.
This also adds a `context.Context` to the `Reconcile` signature, to enable better sharing of logger setup across controllers.
Fixes: https://github.com/knative/pkg/issues/8
Matt Moore