VOL-381 add unum container to support ONOS cluster formation under swarm

Change-Id: Ic260edda19bb199ed040f05164ab605f28c919d0
diff --git a/unum/vendor/github.com/opencontainers/go-digest/verifiers.go b/unum/vendor/github.com/opencontainers/go-digest/verifiers.go
new file mode 100644
index 0000000..f1db6cd
--- /dev/null
+++ b/unum/vendor/github.com/opencontainers/go-digest/verifiers.go
@@ -0,0 +1,31 @@
+package digest
+
+import (
+	"hash"
+	"io"
+)
+
+// Verifier presents a general verification interface to be used with message
+// digests and other byte stream verifications. Users instantiate a Verifier
+// from one of the various methods, write the data under test to it then check
+// the result with the Verified method.
+type Verifier interface {
+	io.Writer
+
+	// Verified will return true if the content written to Verifier matches
+	// the digest.
+	Verified() bool
+}
+
+type hashVerifier struct {
+	digest Digest
+	hash   hash.Hash
+}
+
+func (hv hashVerifier) Write(p []byte) (n int, err error) {
+	return hv.hash.Write(p)
+}
+
+func (hv hashVerifier) Verified() bool {
+	return hv.digest == NewDigest(hv.digest.Algorithm(), hv.hash)
+}