ioworker: Add RecocoServerWorker

It's just a class which inherits both TCPServerWorker and RecocoIOWorker.
It turns out this is useful on its own and there's often no need to
further subclass it, so we might as well include it ourselves.

pox/lib/ioworker/workers.py

@@ -101,6 +101,13 @@ def _do_accept (self, loop, socket):
     return out
 
 
+class RecocoServerWorker (TCPServerWorker, RecocoIOWorker):
+  """
+  Recoco TCP server worker
+  """
+  pass
+
+
 class PersistentIOWorker (RecocoIOWorker, LoggerBase):
   """
   An IOWorker which opens a duplicate of itself when it closes