expand websockets-pubsub tests

[michielbdejong]

In #2 there is only one websockets-pubsub test; we should add ones that test subscribing to a container vs. to a resource, create/update/delete, container create/delete, and WebSockets access tickets with read, write-only, no permissions, permissions on the container, default permissions on the resource, accessTo permissions on the resource.

[michielbdejong]

should also test the Updates-Via header