Structure + Kramdown + Images

Big changes (structural, and preparing styles and designs for images). Any thoughts @jeancflanagan?

New:

- yyyy/title-of-post scheme (good for creating /yyyy archive indexes at some point)
- kramdown instead of maruku (hopefully an improvement)
- CSS fixes
- figures/figcaptions for images, styled
- component-based build so that items are more interchangable as variables
- atom/rss enabled, provisionally