Add GitHub Ribbon to our lessons

- For small screen, preserve margin.
- Use css-beautify

Backport of 9a19e91 from swcarpentry/site.

All credits to Abigail Cabunoc <abigail.cabunoc@oicr.on.ca>
for the awesome work with CSS.

Add CSS media query to improve logo position

*   Indenting error output cells
*   Removing explicit 'level' keys from Markdown files
*   Storing the generated files so that people who don't use those tools won't have to regenerate them.
*   Modifying .gitignore to reflect this.
*   Updating the Makefile to run Jekyll exactly once.
*   Command to install on the server
*   No longer worrying about making a page of images
*   Better (more guessable) name for the target that builds the website
*   Fixing image paths
*   Fixing up glossary entries

**Note**: This is a prototype.

Instead of "In" and "Out" use arrow to mark the input and output
of IPython lessons.

To construct the arrows we only use CSS.

    (instead of using %include directives).
2.  Deleting unused include files containing general bootcamp information.
3.  Leaving the setup instruction snippets in place for now.
4.  Modifying CSS to format things more cleanly now that they're inlined.

When using large font it will overflow the width so I add
max-width in the css.

The 'box' class overflow the window width for some screen size.
This patch fix it using CSS media query.