Automatic merge from submit-queue
Namespace certificates API group
New API groups should follow best-practices for naming, including using DNS names within the k8s.io namespace
```release-note
The certificates API group has been renamed to certificates.k8s.io
```
Running tests rebuilds almost everything. Most unit tests do not need to be
rebuilt. This installs test artifacts and makes subsequent test runs as much
as 6x faster. I saw pkg/apiserver tests drop from 30+ seconds to 5 seconds.
This allows us to start building real dependencies into Makefile.
Leave old hack/* scripts in place but advise to use 'make'. There are a few
rules that call things like 'go run' or 'build/*' that I left as-is for now.