updating googleapis/gnostic to v0.1.0

per https://github.com/googleapis/gnostic/releases/tag/v0.1.0, the
v0.1.0 was made specifically for use by k8s, but we still seem to be
using a random SHA. Let's try to switch to a tagged version.

vendor/github.com/googleapis/gnostic/compiler/reader.go

@@ -15,6 +15,7 @@
 package compiler
 
 import (
+	"errors"
 	"fmt"
 	"gopkg.in/yaml.v2"
 	"io/ioutil"
@@ -53,11 +54,16 @@ func FetchFile(fileurl string) ([]byte, error) {
 		}
 		return bytes, nil
 	}
-	log.Printf("Fetching %s", fileurl)
+	if verboseReader {
+		log.Printf("Fetching %s", fileurl)
+	}
 	response, err := http.Get(fileurl)
 	if err != nil {
 		return nil, err
 	}
+	if response.StatusCode != 200 {
+		return nil, errors.New(fmt.Sprintf("Error downloading %s: %s", fileurl, response.Status))
+	}
 	defer response.Body.Close()
 	bytes, err = ioutil.ReadAll(response.Body)
 	if err == nil {