[renamerOnUpdate] Improve Default Rename Behavior

[8ullyMaguire]

I have noticed that after using this plugin there is a file that ends up being named .mp4 on each folder. This occurs because the plugin works even when the requested fields are empty.

I would like to propose a change to the default behavior of the plugin to improve the user experience. My proposed solution is to change the defaults to only rename organized scenes and perform a dry run by default.

I also suggest checking that all the fields are not empty before renaming. This will reduce the risk of unintended renaming.