The remoteDispatchClientRequest() method is currently hardwired to
assume there is only one type of incoming message, a method call.
To allow for alternate types of incoming messags, the code that is
specific to method calls is being split into a separate method
remoteDispatchClientCall

* qemud/dispatch.c: Move method call specific code out into
  remoteDispatchClientCall. Add a helper remoteSerializeError
  for returning error messages to client