UAS: Cleanup old files/folders when updating #121

Overwriting plugins can cause conflicts in some cases (example below), ideally an update should compare the currently installed plugin with the new version (zip) and delete any directories/files that have been removed.

Example

Example.bundle (v1.0.0)

Example.bundle
 - Contents
    - Code
       - [...]
 - Libraries
   - example
      - one
         - __init__.py

Example.bundle (v1.1.0)

Example.bundle
 - Contents
    - Code
       - [...]
 - Libraries
   - example
      - one.py

Result

Example.bundle
 - Contents
    - Code
       - [...]
 - Libraries
   - example
      - one
         - __init__.py
      - one.py

Attempting to import example.one will always return the example/one/__init__.py module, there is no way to access the updated module.

This was mentioned here as well: https://forums.plex.tv/discussion/comment/1106806/#Comment_1106806