Add OpenShift implementations of ImageSource and ImageDestination

Note that this assumes that both (docker login) and (oc login) has
happened, the credentials can be read from the usual config files,
and that the default OpenShift instance should be used.

This includes copy&pasted/modified/simplified code from OpenShift
and Kubernetes, primarily for config file parsing and setting up
TLS and HTTP authentication.

This is much smaller than linking to the upstream OpenShift client
libraries, which via various abstractions and registration drag in much
(dozens of megabytes) more code.

The primary loss from this simplification is automatic conversions
between various versions of the API objects, both for the REST API and
for local configuration storage.

This does not contain downloading/uploading signatures, which depends on
server-side support.

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

@@ -0,0 +1,99 @@
+// 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) (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); err != nil {
+				return
+			}
+		}
+	case reflect.Map:
+		for _, key := range src.MapKeys() {
+			srcElement := src.MapIndex(key)
+			if !srcElement.IsValid() {
+				continue
+			}
+			dstElement := dst.MapIndex(key)
+			switch reflect.TypeOf(srcElement.Interface()).Kind() {
+			case reflect.Struct:
+				fallthrough
+			case reflect.Map:
+				if err = deepMerge(dstElement, srcElement, visited, depth+1); err != nil {
+					return
+				}
+			}
+			if !dstElement.IsValid() {
+				dst.SetMapIndex(key, srcElement)
+			}
+		}
+	case reflect.Ptr:
+		fallthrough
+	case reflect.Interface:
+		if src.IsNil() {
+			break
+		} else if dst.IsNil() {
+			if dst.CanSet() && isEmptyValue(dst) {
+				dst.Set(src)
+			}
+		} else if err = deepMerge(dst.Elem(), src.Elem(), visited, depth+1); err != nil {
+			return
+		}
+	default:
+		if dst.CanSet() && !isEmptyValue(src) {
+			dst.Set(src)
+		}
+	}
+	return
+}
+
+// Merge sets fields' values in dst from src if they have a zero
+// value of their type.
+// 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 {
+	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)
+}