New home page

Fixes #70. This should be merged after #293.

- [x] Desktop styles
- [x] Tablet styles
- [x] Mobile styles
- [x] Test in IE 8 - 11
- [ ] Fix HTML linter issues
- [ ] Fix media queries in IE 8
What's our latest policy on checking in generated files like *.css vs just the raw source *.scss files and having Grunt generate the output?