Register GCP auth plugin

As described here hashicorp/terraform#15244 (comment)
client-go doesnt enable GCP auth plugin by default. We have to do it explicitly

Author: e-max

kubernetes/provider.go

@@ -9,6 +9,7 @@ import (
 	"github.com/hashicorp/terraform/helper/schema"
 	"github.com/hashicorp/terraform/terraform"
 	"github.com/mitchellh/go-homedir"
+	_ "k8s.io/client-go/plugin/pkg/client/auth/gcp"
 	restclient "k8s.io/client-go/rest"
 	"k8s.io/client-go/tools/clientcmd"
 	clientcmdapi "k8s.io/client-go/tools/clientcmd/api"

vendor/k8s.io/client-go/plugin/pkg/client/auth/gcp/OWNERS

@@ -1483,6 +1483,12 @@
 			"version": "v3.0.0-beta.0",
 			"versionExact": "v3.0.0-beta.0"
 		},
+		{
+			"checksumSHA1": "FSBbUnlpHyGrcgAKYO6+nFtlNQs=",
+			"path": "k8s.io/client-go/plugin/pkg/client/auth/gcp",
+			"revision": "ca90456a21c1db4b5b1dadff1dbcc6f75692d0ee",
+			"revisionTime": "2017-03-02T18:21:54Z"
+		},
 		{
 			"checksumSHA1": "WKKCrNPVWbJYm1im1DA9145z6xI=",
 			"path": "k8s.io/client-go/rest",