Use Assemble to build same pages.

This includes breaking out page regions into more modular "partials" for better maintainability. This is kind of meta-work, but it will enable us to use these sample pages as a style guide later on.
Restructuring sass files to simplify a bit.
Convert HTML partials to Handlebars.
SVG version of the UCSC stacked mark.
Convert sample pages to assemble, part 2.
Modified format for billboard display.
News article teasers will need some HTML changes.