Decouple apiserver from codec implementation

The apiserver on initialization must be provided with a codec
for encoding and decoding all handled objects including api.Status
and api.ServerOp.  In addition, the RESTStorage Extract() method
has been changed to New(), which returns a pointer object that the
codec must decode into (the internal object).  Switched registry
methods to use pointers for Create/Update instead of values.

pkg/apiserver/watch_test.go

@@ -42,7 +42,7 @@ func TestWatchWebsocket(t *testing.T) {
 	simpleStorage := &SimpleRESTStorage{}
 	handler := New(map[string]RESTStorage{
 		"foo": simpleStorage,
-	}, "/prefix/version")
+	}, codec, "/prefix/version")
 	server := httptest.NewServer(handler)
 
 	dest, _ := url.Parse(server.URL)
@@ -92,7 +92,7 @@ func TestWatchHTTP(t *testing.T) {
 	simpleStorage := &SimpleRESTStorage{}
 	handler := New(map[string]RESTStorage{
 		"foo": simpleStorage,
-	}, "/prefix/version")
+	}, codec, "/prefix/version")
 	server := httptest.NewServer(handler)
 	client := http.Client{}