Class for the admin menu
Shortcode all contained in one class
Introduced the addons class

This class handles all of the registered Vimeography addons that hook in to the Vimeography plugin load with `do_action('vimeography/load-addon-plugin')`

This action uses the commented headers of the calling file to determine more information about the plugin.

This file also allows Vimeography to set the active Vimeography theme, so we know which one to use while rendering the galleries.
Functions to perform on admin_init hook
Code formatting
Add wp-list-table class to table
Get the themes from the addons class
Use the addons class to find the themes
Update the asset url
Refactor the renderer class

A few things introduced here:

  - Use the addons class to get the active theme headers
  - Break up the procedural code into different functions
  - Update some code formatting
  - use the `get_class` function to get the name of the class that the custom stylesheets depend on instead of building it the hacky old way.
Switch to EDD Software Licensing

This change has been a long time coming, and has been decided upon mostly because I do not want to continue to manage my own software licensing system any longer. I've found that it impedes on my ability to focus on core plugin development.

These changes will be thoroughly unit tested to ensure they are rock solid, but the introduced code feels good so far.
Added first unit tests.

There is a lot of learning to be had here, so I will make sure to commit often here and detail the changes made to these tests.