Combine the fields that will be used for content transformation
(content-type, codec, and group version) into a single struct in client,
and then pass that struct into the rest client and request. Set the
content-type when sending requests to the server, and accept the content
type as primary.
Will form the foundation for content-negotiation via the client.
The current executor structure is too dependent on client.Request
and client.Config. In order to do an attach from the server, it needs
to be possible to create an Executor from crypto/tls#TLSConfig and to
bypassing having a client.Request.
Changes:
* remotecommand.spdyExecutor - handles upgrading a request to SPDY and getting a connection
* remotecommand.NewAttach / New - moved to exec / portforward / attach since they handle requests
* Remove request.Upgrade() - it's too coupled to SPDY, and can live with the spdyExecutor
* Add request.VersionedParams(runtime.Object, runtime.ObjectConvertor) to handle object -> query transform
Clayton Coleman