diff --git a/vendor/github.com/golang/protobuf/ptypes/timestamp.go b/vendor/github.com/golang/protobuf/ptypes/timestamp.go
new file mode 100644
index 0000000..026d0d4
--- /dev/null
+++ b/vendor/github.com/golang/protobuf/ptypes/timestamp.go
@@ -0,0 +1,103 @@
+// Copyright 2016 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package ptypes
+
+import (
+	"errors"
+	"fmt"
+	"time"
+
+	timestamppb "github.com/golang/protobuf/ptypes/timestamp"
+)
+
+// Range of google.protobuf.Duration as specified in timestamp.proto.
+const (
+	// Seconds field of the earliest valid Timestamp.
+	// This is time.Date(1, 1, 1, 0, 0, 0, 0, time.UTC).Unix().
+	minValidSeconds = -62135596800
+	// Seconds field just after the latest valid Timestamp.
+	// This is time.Date(10000, 1, 1, 0, 0, 0, 0, time.UTC).Unix().
+	maxValidSeconds = 253402300800
+)
+
+// Timestamp converts a timestamppb.Timestamp to a time.Time.
+// It returns an error if the argument is invalid.
+//
+// Unlike most Go functions, if Timestamp returns an error, the first return
+// value is not the zero time.Time. Instead, it is the value obtained from the
+// time.Unix function when passed the contents of the Timestamp, in the UTC
+// locale. This may or may not be a meaningful time; many invalid Timestamps
+// do map to valid time.Times.
+//
+// A nil Timestamp returns an error. The first return value in that case is
+// undefined.
+func Timestamp(ts *timestamppb.Timestamp) (time.Time, error) {
+	// Don't return the zero value on error, because corresponds to a valid
+	// timestamp. Instead return whatever time.Unix gives us.
+	var t time.Time
+	if ts == nil {
+		t = time.Unix(0, 0).UTC() // treat nil like the empty Timestamp
+	} else {
+		t = time.Unix(ts.Seconds, int64(ts.Nanos)).UTC()
+	}
+	return t, validateTimestamp(ts)
+}
+
+// TimestampNow returns a google.protobuf.Timestamp for the current time.
+func TimestampNow() *timestamppb.Timestamp {
+	ts, err := TimestampProto(time.Now())
+	if err != nil {
+		panic("ptypes: time.Now() out of Timestamp range")
+	}
+	return ts
+}
+
+// TimestampProto converts the time.Time to a google.protobuf.Timestamp proto.
+// It returns an error if the resulting Timestamp is invalid.
+func TimestampProto(t time.Time) (*timestamppb.Timestamp, error) {
+	ts := &timestamppb.Timestamp{
+		Seconds: t.Unix(),
+		Nanos:   int32(t.Nanosecond()),
+	}
+	if err := validateTimestamp(ts); err != nil {
+		return nil, err
+	}
+	return ts, nil
+}
+
+// TimestampString returns the RFC 3339 string for valid Timestamps.
+// For invalid Timestamps, it returns an error message in parentheses.
+func TimestampString(ts *timestamppb.Timestamp) string {
+	t, err := Timestamp(ts)
+	if err != nil {
+		return fmt.Sprintf("(%v)", err)
+	}
+	return t.Format(time.RFC3339Nano)
+}
+
+// validateTimestamp determines whether a Timestamp is valid.
+// A valid timestamp represents a time in the range [0001-01-01, 10000-01-01)
+// and has a Nanos field in the range [0, 1e9).
+//
+// If the Timestamp is valid, validateTimestamp returns nil.
+// Otherwise, it returns an error that describes the problem.
+//
+// Every valid Timestamp can be represented by a time.Time,
+// but the converse is not true.
+func validateTimestamp(ts *timestamppb.Timestamp) error {
+	if ts == nil {
+		return errors.New("timestamp: nil Timestamp")
+	}
+	if ts.Seconds < minValidSeconds {
+		return fmt.Errorf("timestamp: %v before 0001-01-01", ts)
+	}
+	if ts.Seconds >= maxValidSeconds {
+		return fmt.Errorf("timestamp: %v after 10000-01-01", ts)
+	}
+	if ts.Nanos < 0 || ts.Nanos >= 1e9 {
+		return fmt.Errorf("timestamp: %v: nanos not in range [0, 1e9)", ts)
+	}
+	return nil
+}