diff --git a/vendor/github.com/grpc-ecosystem/go-grpc-middleware/util/metautils/nicemd.go b/vendor/github.com/grpc-ecosystem/go-grpc-middleware/util/metautils/nicemd.go
new file mode 100644
index 0000000..a277bee
--- /dev/null
+++ b/vendor/github.com/grpc-ecosystem/go-grpc-middleware/util/metautils/nicemd.go
@@ -0,0 +1,126 @@
+// Copyright 2016 Michal Witkowski. All Rights Reserved.
+// See LICENSE for licensing terms.
+
+package metautils
+
+import (
+	"strings"
+
+	"golang.org/x/net/context"
+	"google.golang.org/grpc/metadata"
+)
+
+// NiceMD is a convenience wrapper definiting extra functions on the metadata.
+type NiceMD metadata.MD
+
+// ExtractIncoming extracts an inbound metadata from the server-side context.
+//
+// This function always returns a NiceMD wrapper of the metadata.MD, in case the context doesn't have metadata it returns
+// a new empty NiceMD.
+func ExtractIncoming(ctx context.Context) NiceMD {
+	md, ok := metadata.FromIncomingContext(ctx)
+	if !ok {
+		return NiceMD(metadata.Pairs())
+	}
+	return NiceMD(md)
+}
+
+// ExtractOutgoing extracts an outbound metadata from the client-side context.
+//
+// This function always returns a NiceMD wrapper of the metadata.MD, in case the context doesn't have metadata it returns
+// a new empty NiceMD.
+func ExtractOutgoing(ctx context.Context) NiceMD {
+	md, ok := metadata.FromOutgoingContext(ctx)
+	if !ok {
+		return NiceMD(metadata.Pairs())
+	}
+	return NiceMD(md)
+}
+
+// Clone performs a *deep* copy of the metadata.MD.
+//
+// You can specify the lower-case copiedKeys to only copy certain whitelisted keys. If no keys are explicitly whitelisted
+// all keys get copied.
+func (m NiceMD) Clone(copiedKeys ...string) NiceMD {
+	newMd := NiceMD(metadata.Pairs())
+	for k, vv := range m {
+		found := false
+		if len(copiedKeys) == 0 {
+			found = true
+		} else {
+			for _, allowedKey := range copiedKeys {
+				if strings.ToLower(allowedKey) == strings.ToLower(k) {
+					found = true
+					break
+				}
+			}
+		}
+		if !found {
+			continue
+		}
+		newMd[k] = make([]string, len(vv))
+		copy(newMd[k], vv)
+	}
+	return NiceMD(newMd)
+}
+
+// ToOutgoing sets the given NiceMD as a client-side context for dispatching.
+func (m NiceMD) ToOutgoing(ctx context.Context) context.Context {
+	return metadata.NewOutgoingContext(ctx, metadata.MD(m))
+}
+
+// ToIncoming sets the given NiceMD as a server-side context for dispatching.
+//
+// This is mostly useful in ServerInterceptors..
+func (m NiceMD) ToIncoming(ctx context.Context) context.Context {
+	return metadata.NewIncomingContext(ctx, metadata.MD(m))
+}
+
+// Get retrieves a single value from the metadata.
+//
+// It works analogously to http.Header.Get, returning the first value if there are many set. If the value is not set,
+// an empty string is returned.
+//
+// The function is binary-key safe.
+func (m NiceMD) Get(key string) string {
+	k, _ := encodeKeyValue(key, "")
+	vv, ok := m[k]
+	if !ok {
+		return ""
+	}
+	return vv[0]
+}
+
+// Del retrieves a single value from the metadata.
+//
+// It works analogously to http.Header.Del, deleting all values if they exist.
+//
+// The function is binary-key safe.
+
+func (m NiceMD) Del(key string) NiceMD {
+	k, _ := encodeKeyValue(key, "")
+	delete(m, k)
+	return m
+}
+
+// Set sets the given value in a metadata.
+//
+// It works analogously to http.Header.Set, overwriting all previous metadata values.
+//
+// The function is binary-key safe.
+func (m NiceMD) Set(key string, value string) NiceMD {
+	k, v := encodeKeyValue(key, value)
+	m[k] = []string{v}
+	return m
+}
+
+// Add retrieves a single value from the metadata.
+//
+// It works analogously to http.Header.Add, as it appends to any existing values associated with key.
+//
+// The function is binary-key safe.
+func (m NiceMD) Add(key string, value string) NiceMD {
+	k, v := encodeKeyValue(key, value)
+	m[k] = append(m[k], v)
+	return m
+}