Fix Preferences to Use New NetworkTables Interface

[stulewin]

Using default Table of "Preferences" not "501Prefs". Not sure methods are at all right.

This is code snippet from Chief Delphi question:
` NetworkTableInstance inst = NetworkTableInstance.getDefault();
NetworkTable table = inst.getTable("501Prefs");

  StringTopic configTopic = table.getStringTopic("config");
  configTopic.setPersistent(true);
  configTopic.setRetained(true);

  configPub = configTopic.publish();
  configPub.set(VersionInfo.version);
  configPub.close();`

Still need to publish before persist.
Also use the tree hierarchy instead of dot name notation. "501Prefs/Arm/P" not "Preferences/Arm.P"