Feature Release - Added cleanup capabilities!!! Yaaaassss

A decent amount of updates here:

• Fixed possible bug with post_type_exists checks on multisite installs.
• Added cleanup method to allow users to undo/remove posts, terms, and media that was added via this generator. This is not backwards compatible, with earlier versions, sorry guys!
• Added post_status flag for generating posts, you can now set your own status.
  Note: status does not validate, so you can technically set this to anything, its up to you as a developer to expose custom statuses in the admin.
• Added taxonomy validation: Script will now validate if a taxonomy is even registered, and allow you to continue if you want.