Unify assets to cdn.freecodecamp.org

We should unify static assets to use the cdn.freecodecamp.org CDN. The CDN repo is here: https://github.com/freeCodeCamp/cdn

List of assets not using cdn.freecodecamp.org

Edit: all the below projects have been updated.

### Build a Tribute Page:

https://codepen.io/freeCodeCamp/pen/zNqgVx

The image is on flickr. Needs to be moved to CDN and have the Codepen updated.

https://c2.staticflickr.com/4/3689/10613180113_fdf7bcd316_b.jpg

Build a Product Landing Page:

https://codepen.io/freeCodeCamp/pen/RKRbwL

The logo image is on AWS. Needs to be moved to CDN and have the Codepen updated.

https://s3.amazonaws.com/freecodecamp/original_trombones.png

Build a Personal Portfolio Webpage:

https://codepen.io/freeCodeCamp/pen/zNBOYG

Is using raw.githubusercontent.com. The images are already in the CDN repo but the Codepen needs to be updated to use cdn.freecodecamp.org instead.

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If anyone knows of other assets that should be added to the list please post them here.

[lasjorg]

I have updated the initial post to reflect the updates done.

I will keep this issue open for now just in case anyone finds other assets that need to be updated. Just so we can keep a list of them here.

[lasjorg]

I created the PR: https://github.com/freeCodeCamp/cdn/pull/65

It took a little longer than expected as I had to add some environment variables to GitPod for it to work with GitHub private emails. I will post a link to the GitPod issue https://github.com/gitpod-io/gitpod/issues/387 with the info just in case anyone else needs it.