fix(jekyll): Output non-defaulted frontmatter
fix(jekyll): Output non-defaulted frontmatter

The previous frontmatter that was outputted included all defaults being
set, even when not all the information was present to do so (like the
file path).  This will get more correct cobalt behavior.

Another bug that still needs processing is to output `wildwest` format
rather than the internal format.

Also, various style refactorings were done.

cobalt-org/cobalt.rs,cobalt-org/cobalt.rs,cobalt-org/cobalt.rs,cobalt-org/cobalt.rs