Switch to jQuery.image

[mjangda]

jQuery.image is probably a better option for handling lazy-loading and we can drop the dependency on sonar.

[mjangda]

Some alternate libs:

http://www.appelsiini.net/projects/lazyload
http://luis-almeida.github.io/unveil/
https://github.com/aFarkas/lazysizes
https://github.com/dinbror/blazy/

[BrookeDot]

I'm actually using a slightly modified version of this plugin on a site using the LazyLoad JavaScript from verlok. https://github.com/verlok/lazyload

I think if we switched to this script we could drop jQuery and sonar as well as add support for native lazyload fixing #19.

Thoughts?