Update vendor with go dep

This fix updates vendor with `go dep`

Signed-off-by: Yong Tang <yong.tang.github@outlook.com>

vendor/github.com/imdario/mergo/merge.go

@@ -0,0 +1,123 @@
+// Copyright 2013 Dario Castañé. All rights reserved.
+// Copyright 2009 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.
+
+// Based on src/pkg/reflect/deepequal.go from official
+// golang's stdlib.
+
+package mergo
+
+import (
+	"reflect"
+)
+
+// Traverses recursively both values, assigning src's fields values to dst.
+// The map argument tracks comparisons that have already been seen, which allows
+// short circuiting on recursive types.
+func deepMerge(dst, src reflect.Value, visited map[uintptr]*visit, depth int, overwrite bool) (err error) {
+	if !src.IsValid() {
+		return
+	}
+	if dst.CanAddr() {
+		addr := dst.UnsafeAddr()
+		h := 17 * addr
+		seen := visited[h]
+		typ := dst.Type()
+		for p := seen; p != nil; p = p.next {
+			if p.ptr == addr && p.typ == typ {
+				return nil
+			}
+		}
+		// Remember, remember...
+		visited[h] = &visit{addr, typ, seen}
+	}
+	switch dst.Kind() {
+	case reflect.Struct:
+		for i, n := 0, dst.NumField(); i < n; i++ {
+			if err = deepMerge(dst.Field(i), src.Field(i), visited, depth+1, overwrite); err != nil {
+				return
+			}
+		}
+	case reflect.Map:
+		for _, key := range src.MapKeys() {
+			srcElement := src.MapIndex(key)
+			if !srcElement.IsValid() {
+				continue
+			}
+			dstElement := dst.MapIndex(key)
+			switch srcElement.Kind() {
+			case reflect.Chan, reflect.Func, reflect.Map, reflect.Ptr, reflect.Interface, reflect.Slice:
+				if srcElement.IsNil() {
+					continue
+				}
+				fallthrough
+			default:
+				if !srcElement.CanInterface() {
+					continue
+				}
+				switch reflect.TypeOf(srcElement.Interface()).Kind() {
+				case reflect.Struct:
+					fallthrough
+				case reflect.Ptr:
+					fallthrough
+				case reflect.Map:
+					if err = deepMerge(dstElement, srcElement, visited, depth+1, overwrite); err != nil {
+						return
+					}
+				}
+			}
+			if !isEmptyValue(srcElement) && (overwrite || (!dstElement.IsValid() || isEmptyValue(dst))) {
+				if dst.IsNil() {
+					dst.Set(reflect.MakeMap(dst.Type()))
+				}
+				dst.SetMapIndex(key, srcElement)
+			}
+		}
+	case reflect.Ptr:
+		fallthrough
+	case reflect.Interface:
+		if src.IsNil() {
+			break
+		} else if dst.IsNil() {
+			if dst.CanSet() && (overwrite || isEmptyValue(dst)) {
+				dst.Set(src)
+			}
+		} else if err = deepMerge(dst.Elem(), src.Elem(), visited, depth+1, overwrite); err != nil {
+			return
+		}
+	default:
+		if dst.CanSet() && !isEmptyValue(src) && (overwrite || isEmptyValue(dst)) {
+			dst.Set(src)
+		}
+	}
+	return
+}
+
+// Merge will fill any empty for value type attributes on the dst struct using corresponding
+// src attributes if they themselves are not empty. dst and src must be valid same-type structs
+// and dst must be a pointer to struct.
+// It won't merge unexported (private) fields and will do recursively any exported field.
+func Merge(dst, src interface{}) error {
+	return merge(dst, src, false)
+}
+
+// MergeWithOverwrite will do the same as Merge except that non-empty dst attributes will be overriden by
+// non-empty src attribute values.
+func MergeWithOverwrite(dst, src interface{}) error {
+	return merge(dst, src, true)
+}
+
+func merge(dst, src interface{}, overwrite bool) error {
+	var (
+		vDst, vSrc reflect.Value
+		err        error
+	)
+	if vDst, vSrc, err = resolveValues(dst, src); err != nil {
+		return err
+	}
+	if vDst.Type() != vSrc.Type() {
+		return ErrDifferentArgumentsTypes
+	}
+	return deepMerge(vDst, vSrc, make(map[uintptr]*visit), 0, overwrite)
+}