New Features

[caleuanhopkins]

Hey guys,

I still use this plugin on almost every project I use, I know it's fallen down your list of things to manage. I'm more than happy to help support and manage the project if it's not something you guys spend much time with. Like I said, I deal with the plugin on almost every project I do so I've got time to manage the project.

Anyway, this PR adds to features I've been manually adding in myself for a while now:

1. Responsive Images - Allow multiple image handling based on screen sizes and follows Eric Portis' suggestions in his article Responsive Images in Practice
2. Non-Background - This is to use Anystretch for images in material style card designs. Might seem a bit redundant, but when working with CMS and clients who use images which don't match the ratio which is used in the design. (maybe this is just a personal option)

Any questions, feel free to hit me up.