Refactor the client (again) to better support auth

* Allows consumers to provide their own transports for common cases.
* Supports KUBE_API_VERSION on test cases for controlling which
  api version they test against
* Provides a common flag registration method for CLIs that need
  to connect to an API server (to avoid duplicating flags)
* Ensures errors are properly returned by the server
* Add a Context field to client.Config

pkg/client/flags.go

@@ -0,0 +1,29 @@
+/*
+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 client
+
+// FlagSet abstracts the flag interface for compatibility with both Golang "flag"
+// and cobra pflags (Posix style).
+type FlagSet interface {
+	StringVar(p *string, name, value, usage string)
+}
+
+// BindClientConfigFlags registers a standard set of CLI flags for connecting to a Kubernetes API server.
+func BindClientConfigFlags(flags FlagSet, config *Config) {
+	flags.StringVar(&config.Host, "master", config.Host, "The address of the Kubernetes API server")
+	flags.StringVar(&config.Version, "api_version", config.Version, "The API version to use when talking to the server")
+}