Enable Lazy loading images

[derbyshire10]

Added lazy loading so images are only loaded when they are going to come into view instead of all at once. This will improve the page load times.

[gabeseltzer]

I appreciate your help, but I don't want to add the lazy loading tag to all the images like this. We're looking into other ways to speed up the page loading process and I also want to avoid lazy loading to make the scrolling experience better.