Reorganizing material to put page source in sub-directory:

* Add `.nojekyll` to stop GitHub trying to compile.
* Get rid of Jekyll `_config.yml`.
* Create placeholder `css` and `img` directories.
* Create `pages` directory with source for web pages.
* Move all Markdown files into `pages`.
* Move `tools` into `pages` (because that's where people will mostly work).
* Move `_includes` and `_layouts` into `pages` (because that's where we'll compile).
Rationalizing tools.

1. Moving all commands into a Makefile (because we're handling file dependencies, and that's the right tool for it).
2. Ignoring the .html files produced in the root directory for now.
3. Switching to a single layout modeled on that used for workshop websites - will need to update this.
Bringing in description of lesson structure
Including things in templates
Example of including image in file
Another editing pass on the explanation for the template
Merge pull request #3 from gvwilson/moving-material-into-src

Putting template into final [sic] form
Overly-zealous .gitignore had excluded the `_layouts` directory - this PR fixes it.

1. Modify `.gitignore` to only ignore HTML files in the current directory.
2. Add `_includes/page.html` template.
Modify `.gitignore` so that it *doesn't* ignore HTML files.

The HTML files in the root directory of this repository don't belong in version control,
since they are built from the demonstration files in `pages` rather than from real lessons.
However, the HTML files in the root of actual lessons definitely *do* belong in the repo,
so the `.gitignore` shouldn't ignore them.
Merge pull request #7 from gvwilson/gh-pages

Include standard page layout
Adding missing CSS files.

1. Bringing in Bootstrap CSS files.
2. Merging swc.css and swc-bootstrap.css from 'bc' repository.
3. Updating _includes/header.html to refer to the right files.
Preparing to create motivational slides
Converting `motivation.md` to use slides template.

Also modifed the Makefile to use the slides template for this file
instead of the generic template.

Note that we do not need a Markdown extension for deck.js because
Pandoc is doing Markdown-to-HTML conversion for us.
Merge pull request #13 from gvwilson/adding-slides

Adding slides
Fix layout to follow bc CSS
Merge pull request #14 from r-gaia-cs/fix-layout

Fix layout to follow bc CSS
Merge pull request #12 from gvwilson/adding-css-files

Adding missing CSS files.
pandoc filter to convert blockquotes to divs

This filter converts all blockquote-with-attributes to
div-with-attributes.

A blockquote-with-attributes is defined as a blockquote that has a
header with attributes defined on it as it's first element, e.g.

    > # valid blockquote {.class}
    > text

This example would be converted into this markdown:

    <div class='class' id=id>
    # valid blockquote
    text
    </div>

And the equivalent html.

The class must be one of the allowed classes defined in the filter (i.e.
one of 'callout', 'objectives' or 'challenge').
add pandoc dependencies to README
Merge pull request #9 from aaren/gh-pages

[RDY] pandoc filter to convert blockquotes to divs