title: IxNetwork python library: can't see traffic items in loaded ixncfg-file
body: <p>I'm using IxNetwork python library for working with IxNetwork. After loading ixncfg-file with configuration, I can read via library ports, protocols, but not traffic items.</p>
  
  <p>I want just load prepared ixncfg-file with all configration: ports, protocols, traffic items, flow groups. Start protocols; Regenerate traffic items; Apply changes in traffic items; Start traffic; Stop traffic after some time; Gather statistics</p>
  
  <p>I'm stuck with traffic items. getList method for traffic return nothing - so I can't manipulate traffic items from ixncfg-file</p>
  
  <pre class="lang-py prettyprint-override"><code>import IxNetwork
  ixNServer = 'localhost'
  ixNPort = '8009' 
  ixNet = IxNetwork.IxNet() 
  ixNet.connect(ixNServer, '-port', ixNPort) 
  ixNet.execute('newConfig') 
  fileName = r'/home/ccap/IxNetworkConfig.ixncfg' 
  fileHnd = ixNet.readFrom(fileName) 
  ixNet.execute('loadConfig', fileHnd) 
  ixNet.execute('startAllProtocols') 
  
  traffic = ixNet.getList(ixNet.getRoot(), 'traffic')
  traffic_items = ixNet.getList(traffic[0], 'trafficItem') 
  
  traffic_items list is empty
  
  but it should return something like this:
  ['::ixNet::OBJ-/traffic/trafficItem:1',
   '::ixNet::OBJ-/traffic/trafficItem:2',
   '::ixNet::OBJ-/traffic/trafficItem:3',
   '::ixNet::OBJ-/traffic/trafficItem:4']
  </code></pre>