Allow to redirect bus request
In order to easy configuration of a second thread-less server [1], I think we could allow to configure an URL host to redirect bus request to.
But to get this redirect working on web client, the server needs to support CORS [2]. I think we could have a simple global support once an origin is configured, it is allowed all the method and headers. For those who want more controls, they could to use an HTTP proxy.
[1] https://discuss.tryton.org/t/thread-less-long-polling/960
[2] https://en.wikipedia.org/wiki/Cross-origin_resource_sharing