This also incorporates the version string into the package name so
that incompatibile versions will fail to connect.
Arbitrary choices:
- The proto3 package name is runtime.v1alpha2. The proto compiler
normally translates this to a go package of "runtime_v1alpha2", but
I renamed it to "v1alpha2" for consistency with existing packages.
- kubelet/apis/cri is used as "internalapi". I left it alone and put the
public "runtimeapi" in kubelet/apis/cri/runtime.
* Properly return ImageNotFoundError
* Support inject "Images" or "ImageInspects" and keep both in sync.
* Remove the FakeDockerPuller and let FakeDockerClient subsumes its
functinality. This reduces the overhead to maintain both objects.
* Various small fixes and refactoring of the testing utils.
