diff --git a/vendor/github.com/mongodb/mongo-go-driver/bson/unmarshal.go b/vendor/github.com/mongodb/mongo-go-driver/bson/unmarshal.go
new file mode 100644
index 0000000..2b3cca8
--- /dev/null
+++ b/vendor/github.com/mongodb/mongo-go-driver/bson/unmarshal.go
@@ -0,0 +1,101 @@
+// Copyright (C) MongoDB, Inc. 2017-present.
+//
+// Licensed under the Apache License, Version 2.0 (the "License"); you may
+// not use this file except in compliance with the License. You may obtain
+// a copy of the License at http://www.apache.org/licenses/LICENSE-2.0
+
+package bson
+
+import (
+	"bytes"
+
+	"github.com/mongodb/mongo-go-driver/bson/bsoncodec"
+	"github.com/mongodb/mongo-go-driver/bson/bsonrw"
+	"github.com/mongodb/mongo-go-driver/bson/bsontype"
+)
+
+// Unmarshaler is an interface implemented by types that can unmarshal a BSON
+// document representation of themselves. The BSON bytes can be assumed to be
+// valid. UnmarshalBSON must copy the BSON bytes if it wishes to retain the data
+// after returning.
+type Unmarshaler interface {
+	UnmarshalBSON([]byte) error
+}
+
+// ValueUnmarshaler is an interface implemented by types that can unmarshal a
+// BSON value representaiton of themselves. The BSON bytes and type can be
+// assumed to be valid. UnmarshalBSONValue must copy the BSON value bytes if it
+// wishes to retain the data after returning.
+type ValueUnmarshaler interface {
+	UnmarshalBSONValue(bsontype.Type, []byte) error
+}
+
+// Unmarshal parses the BSON-encoded data and stores the result in the value
+// pointed to by val. If val is nil or not a pointer, Unmarshal returns
+// InvalidUnmarshalError.
+func Unmarshal(data []byte, val interface{}) error {
+	return UnmarshalWithRegistry(DefaultRegistry, data, val)
+}
+
+// UnmarshalWithRegistry parses the BSON-encoded data using Registry r and
+// stores the result in the value pointed to by val. If val is nil or not
+// a pointer, UnmarshalWithRegistry returns InvalidUnmarshalError.
+func UnmarshalWithRegistry(r *bsoncodec.Registry, data []byte, val interface{}) error {
+	vr := bsonrw.NewBSONDocumentReader(data)
+	return unmarshalFromReader(bsoncodec.DecodeContext{Registry: r}, vr, val)
+}
+
+// UnmarshalWithContext parses the BSON-encoded data using DecodeContext dc and
+// stores the result in the value pointed to by val. If val is nil or not
+// a pointer, UnmarshalWithRegistry returns InvalidUnmarshalError.
+func UnmarshalWithContext(dc bsoncodec.DecodeContext, data []byte, val interface{}) error {
+	vr := bsonrw.NewBSONDocumentReader(data)
+	return unmarshalFromReader(dc, vr, val)
+}
+
+// UnmarshalExtJSON parses the extended JSON-encoded data and stores the result
+// in the value pointed to by val. If val is nil or not a pointer, Unmarshal
+// returns InvalidUnmarshalError.
+func UnmarshalExtJSON(data []byte, canonical bool, val interface{}) error {
+	return UnmarshalExtJSONWithRegistry(DefaultRegistry, data, canonical, val)
+}
+
+// UnmarshalExtJSONWithRegistry parses the extended JSON-encoded data using
+// Registry r and stores the result in the value pointed to by val. If val is
+// nil or not a pointer, UnmarshalWithRegistry returns InvalidUnmarshalError.
+func UnmarshalExtJSONWithRegistry(r *bsoncodec.Registry, data []byte, canonical bool, val interface{}) error {
+	ejvr, err := bsonrw.NewExtJSONValueReader(bytes.NewReader(data), canonical)
+	if err != nil {
+		return err
+	}
+
+	return unmarshalFromReader(bsoncodec.DecodeContext{Registry: r}, ejvr, val)
+}
+
+// UnmarshalExtJSONWithContext parses the extended JSON-encoded data using
+// DecodeContext dc and stores the result in the value pointed to by val. If val is
+// nil or not a pointer, UnmarshalWithRegistry returns InvalidUnmarshalError.
+func UnmarshalExtJSONWithContext(dc bsoncodec.DecodeContext, data []byte, canonical bool, val interface{}) error {
+	ejvr, err := bsonrw.NewExtJSONValueReader(bytes.NewReader(data), canonical)
+	if err != nil {
+		return err
+	}
+
+	return unmarshalFromReader(dc, ejvr, val)
+}
+
+func unmarshalFromReader(dc bsoncodec.DecodeContext, vr bsonrw.ValueReader, val interface{}) error {
+	dec := decPool.Get().(*Decoder)
+	defer decPool.Put(dec)
+
+	err := dec.Reset(vr)
+	if err != nil {
+		return err
+	}
+	err = dec.SetContext(dc)
+	if err != nil {
+		return err
+	}
+
+	return dec.Decode(val)
+}