closes #2224: re-vendor the latest Azure Storage SDK for better performance

Signed-off-by: Yu Wang <yuwa@microsoft.com>

vendor/github.com/Azure/go-autorest/autorest/version.go

@@ -0,0 +1,23 @@
+package autorest
+
+import (
+	"fmt"
+)
+
+const (
+	major        = "7"
+	minor        = "3"
+	patch        = "0"
+	tag          = ""
+	semVerFormat = "%s.%s.%s%s"
+)
+
+var version string
+
+// Version returns the semantic version (see http://semver.org).
+func Version() string {
+	if version == "" {
+		version = fmt.Sprintf(semVerFormat, major, minor, patch, tag)
+	}
+	return version
+}