Version 3 API Update

 - This project has abandoned Imgur API v2 support in favor of v3. There are some major changes that come along with this in the `ImgurDotNet` project.
 - Support has been added for a few more features, including album creation and deletion, uploading images from a direct link URL, and adding images to an album upon creation.
 - The `ImgurDotNetTest` project has been completely overhauled. It is a console application for testing all features of the `ImgurDotNet` project. It provides a list of valid commands for testing, and includes error handling.