Avoid creating uneeded instance of PropertyShellTableFactory

The story here is that we have 2 versions of the ShellTableFactory:
i) OSGi aware
ii) Property based

Our commands always instantiate (ii) and may replace it with when running inside OSGi.
We should make sure that we instantiate (ii) only if no injection takes place (e.g. outside OSGi)

This could be as simple as checking if the factory is null inside the doExecute method and then instantiating (ii).