update README
add support for hidpi screens to image partial
added xlarge work index  page assets, updated large work index assets to improve image quality
moved project page styles into their own SCSS file; other small styling tweaks
updated Highlander Orientation thumb assets
small css bug fixes
make support for xlarge hidpi assets optional; tweak vertial position of gallery controls
add xlarge asset sizes to hero images
Merge pull request #13 from sdillingham/add-hidpi-support

Add hidpi support