Adding a note to remind authors to say what learners are supposed to do in lessons
Merge pull request #2 from gvwilson/gh-pages

Adding a note to remind authors to say what learners are supposed to do in lessons.
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