Improve update demo, support rolling template update

This improves the update demo pretty dramatically.

* Makes the demo more visual, fixes some HTML layout
* Make naming of objects in `kubecfg run <image> <replicas> <controller>` more obvious
* Run update demo without pushing/creating new containers in docker hub (slow)
* Improve e2e tests to actually do the rolling update
Please add:
// TODO(dbsmith): implement directly instead of via Encode/Decode.