Added Plugin Scripts.

After wasting about 2 hours on trying to import the history of these two script files from another repository (and learning stuff about some git commands) I am just adding these files as new.

The output json looks like this: https://github.com/dufferzafar/picard-plugins/blob/master/Plugins.json

To test the scripts, you'll need a folder containing picard plugin files. I have a setup here: https://github.com/dufferzafar/picard-plugins
The folder name has to be the same as the [module_name](https://github.com/musicbrainz/picard/blob/master/picard/plugin.py#L102) only then will we be able to create a matching between the json data and plugin files. This seems like a limitation but I can't think of anything better either.