Add an examples layout.

I know in the past we wanted people to get the files from the repo and use them, but this situation results in too much duplication and also cases where things can break.

This should make everything safer and cleaner.

Also, I removed unused JS assets and only include the ones each example needs. We might be able to drop more JS files if they are not used in some examples like in the Cover example where no JS is needed.

Check the non-whitespace diff

TODO:

• Load our assets with the Jekyll variables and not relative to the files
• See if we can make indentation proper