Build from a `/content` directory

OKAY, this contains a ton of stuff! And I wrote it a while ago, so I have to remember everything I did

## /lib/
I broke the site generation into multiple steps:

- `collect-files.js`: looks in a specific directory and recursively gets all of the relative file paths for everything inside. This is more or less wrapper for glob that makes it easier to do things later in the pipeline.

- `parse-markdown.js`: given a markdown file, tries to extract header information such as `title`, `author`, `date`, and `tags`. Returns all of that metadata, as well as the whole file (as `content` attribute) in an object.

- `generate-templates.js`: handles the registration of partials and makes the various template functions. It also returns the `handlebars` object for use down the pipeline. So for example if you have a couple of templates, `templates/main.html` `templates/post.md` (which can depend on partials) it returns `{ handlebars: <handlebars>, main: <function>, post: <function> }`. The template functions expect an object with the `content` attribute (such as from the output of `parse-markdown.js`), which should be the HTML to go into the page.

- `feed-generator.js`: builds the RSS feed for the posts. Takes the output of `parse-markdown.js`.

- `generate-site-dir.js`: this puts together the pipeline to generate a full site directory. Anything that's in `/content` and isn't a parseable file (currently anything other than `.md` files) gets copied over directly. `.md` files go through the `parse-markdown.js` and are applied to the template functions from `generate-templates.js` to make HTML files which get put written to the same location as the original markdown file.

## /test/

A whole bunch of tests for each of the files/steps in the pipeline!


## /bin/

A `balrog` binary which runs `generate-site-dir.js` with reasonable defaults. This can be run in any folder that has a `content` directory to generate a `site` directory. Also expects `templates` directory, and (optionally) `partials` directory.