Added a CDN

This feature is changing how you can use GenerateBanners.com!

Previously you would:

1. Generate an image using the UI
2. Download it
3. Upload it somewhere so that you can use it on the web
   => Too many steps

Now you can:

1. Generate an image using the UI
2. Use the generated link directly in your open graph tags or your img html tags.
   => A lot easier!

This enabled me to add one simple open graph image on the whole website very easily!