Remove whole piles of cruft from the connection layer. The only thing that was

Remove whole piles of cruft from the connection layer.  The only thing that was
using connectionMade, connectionLost, startedConnecting, clientConnectionLost,
and clientConnectionFailed was the test classes (TestClientFactory,
TestClientProtocol, TestServerFactory, TestServerProtocol), so they were
actually testing lots of code that no-one else was using.  All these classes
have gone, freeing up lots of cruft around.

The useless classes Factory, ServerFactory, ClientFactory, RelocationFactory,
UnixServerConnection, and TCPServerConnection have gone, in favour of passing
the Protocol class directly to SocketListener, and using SocketServerConnection
directly.

connectTransport has gone, in favour of overriding connect directly.

Piles of closedown cruft has gone, as this was only supporting the correct
output of connectionLost events, none of which we need.

Unused SocketServerConnection.{getHost,getPeer} have gone.

Mark some parameters in relocate as unused.

Signed-off-by: Ewan Mellor <ewan@xensource.com>