Auto merge of ycm-core#303 - micbou:python-restart-server, r=Valloric

[READY] Fix RestartServer command in Python completer

`RestartServer` subcommand is not working because the `request_data` parameter is not given to the `RestartServer` method. Since this parameter is not used, remove it.

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ycmd/completers/python/jedi_completer.py

@@ -104,7 +104,7 @@ def ServerIsRunning( self ):
         return False
 
 
-  def RestartServer( self, request_data ):
+  def RestartServer( self ):
     """ Restart the JediHTTP Server. """
     with self._server_lock:
       self._StopServer()