remove py.execnet, substitute py.execnet usages with "execnet" ones.

--HG--
branch : trunk

doc/test/customize.txt

@@ -364,7 +364,7 @@ remote environment.  For this you can implement the newgateway hook:
     def pytest_gwmanage_newgateway(gateway, platinfo):
         """ called after a gateway is instantiated. """
 
-The ``gateway`` object here has a ``spec`` attribute which is an ``py.execnet.XSpec`` 
+The ``gateway`` object here has a ``spec`` attribute which is an ``execnet.XSpec`` 
 object, which has attributes that map key/values as specified from a ``--txspec``
 option. The platinfo object is a dictionary with information about the remote process: 
 

doc/test/funcargs.txt

@@ -165,7 +165,7 @@ and to offer a new mysetup method:
             host = self.config.option.ssh
             if host is None:
                 py.test.skip("specify ssh host with --ssh")
-            return py.execnet.SshGateway(host)
+            return execnet.SshGateway(host)
 
 
 Now any test function can use the ``mysetup.getsshconnection()`` method like this: