Support different transports

[codeliner]

Event streams are polled by the UI. While this is a super simple set up and works out-of-the box with the event store http api, it is also a performance killer and causes a lot of network traffic. As long as it is only used for development purposes I don't see a big issue but you cannot set up stream monitoring on production systems. It would be nice if new events could also be consumed using a socket connection or JSON streaming. One could install a plugin and set up the backend for it if needed.