New website

I rebased the pngsvg branch which includes @BaconRanch's changes and made a few more. This PR supersedes PR #8.

A short summary:

* Added grunt support for development and deployment. Also combined and minified the css/js files reducing the size and number of http requests
* Converted the thumbnails to 8-bit saving 50%

TODO:

- [x] Add Grunt support
- [x] Convert the thumbnails to 8-bit
- [x] Switch to jquery fancybox for the screenshots
- [x] Fix media queries and responsive design
- [x] Switch to normalize.css instead of reset.css
- [x] Clean up style.css and fix issues like missing fallback colors etc. Also switch to hex colors when possible
- [x] Move favicon to root