Support for STOMP over raw TCP connections

[joffrey-bion]

As mentioned in #261, some users would find it useful to connect to STOMP servers via raw TCP connections without any HTTP nor web socket layer.

This is not part of the initial design of Krossbow, but the STOMP layer is not too coupled to the web socket layer, so it should be technically feasible to use the same STOMP code over a raw TCP connection, at least on JVM and maybe native.