Major changes in release 2.0:

* The RemoteCallServer is now based on the SocketServer module, which comes
  with the standard Python distribution.

* Socket connections are more long lived than before. Previously, a new
  connection was established for each request; Now the connection is kept for
  the lifetime of the RemoteCall instance.

* To further capitalize on few connections, several agents may use a single
  remote call instance.

* RemoteCall can now use Unix sockets as transport medium. No support for
  DATAGRAM sockets yet though.

