Make runtime less global for Codec

* Make Codec separate from Scheme
* Move EncodeOrDie off Scheme to take a Codec
* Make Copy work without a Codec
* Create a "latest" package that imports all versions and
  sets global defaults for "most recent encoding"
  * v1beta1 is the current "latest", v1beta2 exists
  * Kill DefaultCodec, replace it with "latest.Codec"
  * This updates the client and etcd to store the latest known version
* EmbeddedObject is per schema and per package now
* Move runtime.DefaultScheme to api.Scheme
* Split out WatchEvent since it's not an API object today, treat it
like a special object in api
* Kill DefaultResourceVersioner, instead place it on "latest" (as the
  package that understands all packages)
* Move objDiff to runtime.ObjectDiff

pkg/api/latest/latest.go

@@ -0,0 +1,37 @@
+/*
+Copyright 2014 Google Inc. All rights reserved.
+
+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
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+package latest
+
+import (
+	"github.com/GoogleCloudPlatform/kubernetes/pkg/api/v1beta1"
+	_ "github.com/GoogleCloudPlatform/kubernetes/pkg/api/v1beta2"
+	"github.com/GoogleCloudPlatform/kubernetes/pkg/runtime"
+)
+
+// Version is the string that represents the current external default version
+var Version = "v1beta1"
+
+// Codec is the default codec for serializing output that should use
+// the latest supported version.  Use this Codec when writing to
+// disk, a data store that is not dynamically versioned, or in tests.
+// This codec can decode any object that Kubernetes is aware of.
+var Codec = v1beta1.Codec
+
+// ResourceVersioner describes a default versioner that can handle all types
+// of versioning.
+// TODO: when versioning changes, make this part of each API definition.
+var ResourceVersioner = runtime.NewJSONBaseResourceVersioner()