Set up code color

Remove border bottom from title

and others small fixes.

Changing sed command used to display help from Makefile.

As per https://github.com/swcarpentry/workshop-template/pull/53,
this PR is more selective about what it does and doesn't print.

Clean CSS file

Improving setup instructions

Multiple changes based on converting Make lesson to template

1.  Moving the build steps up to the top of `README.md`.
2.  Removed the misleading target to run the checking tool (since the tool doesn't actually work).

And taking it out of the auto-displayed list of available commands.

[RDY] 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').

Adding missing CSS files.

Fix layout to follow bc CSS

Adding slides

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.

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.

Include standard page layout

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.

1. Modify `.gitignore` to only ignore HTML files in the current directory.
2. Add `_includes/page.html` template.

Putting template into final [sic] form