Improved the packaging as follows:

- The leoOPML plugin no longer monkey patches any part of the FileCommands
  class. Instead the plugin sets the c.opmlController ivar.

- fc.writeToFileHelper calls c.opmlController.putToOPML(owner=self).

- OpmlController.putToOPML is just PutToOPML(owner) where PutToOPML is a
  class that creates the opml using the owner's put method.

Leo build: 20141020202854