AB#2076: version specific images (#288)

KubernetesVersion sent by the init command now controls
all downloaded binaries, if they depend on the k8s version.

* Move all download links into /internal/versions.
* Unify files in /internal/versions package
* Move image download links into VersionConfigs
and thus make them dependant on the k8s version,
where the image version is specific to the k8s version.
* Don't specify patch version in k8sVersion

bootstrapper/internal/kubernetes/k8sapi/kubectl/client/client_test.go

@@ -245,7 +245,7 @@ func TestGetObjects(t *testing.T) {
 		wantErr          bool
 	}{
 		"GetObjects works on cluster-autoscaler deployment": {
-			wantResources: resources.NewDefaultAutoscalerDeployment(nil, nil, nil),
+			wantResources: resources.NewDefaultAutoscalerDeployment(nil, nil, nil, ""),
 			resourcesYAML: string(nginxDeplYAML),
 			wantErr:       false,
 		},