Update jekyll.
Migrate assets to jekyll-assets.
Link favicon into root directory.
Update README.

* New copyright directories.
* No longer using jekyll plugins.
Change directories to follow conventions.

Directories which aren't going to be in publishes are prefixed with an
underscore.
Concatenate everything into one stylesheet.
Ack ignores _vendor and _site directories.
Convert remaining images over to asset pipeline.
Destroy build directory before building for deploy.
We don't need to explicitly exclude underscored directories.
Rename 404-not-found -> error.
Revert "Rename 404-not-found -> error."

This reverts commit 1bafffcaf4cb3eeaf9f0c5468a19cc1b17353f2e.
Add and configure jekyll-s3.
Update README.

Reference deploying.