server does not handle incoming garbage

[davepacheco]

Original bug report: MORAY-444.

The new fast implementation is careful to validate incoming data and generate errors for invalid data, but the FastServer does not handle all of these cases properly. In particular, if you make an HTTP request to the fast port (for example), the decoder will emit an error reflecting the garbage that came in, but the server doesn't handle that error, so the server crashes anyway.

Instead, the server should listen for errors on each connection's message decoder. On error, it should terminate the connection with connTerminate, just like it does in server.onMessage() when there are other types of protocol errors.

As part of fixing this, we should add a server test case to exercise this case.