Automate navigation in website

[nottrobin]

Here I'm doing quite a few things:

• Move the title of each page into metadata (title: {title})
• Move the description of each page (from index.md that was) into metadata (description: {description})
• Generate the side-nav automatically, based on filenames
• Generate the list in the index page automatically, based on title and description
• Put the page title in its own fancy row, with a nice background
• Change the name of the site to "Web and design practices" (hopefully fixes #117)
• Add jekyll-redirect-from (the only plugin supported by GitHub pages), and redirect /coding/react and /coding/code-formatting to /coding/javascript

QA

sudo gem install jekyll-redirect-from
jekyll serve

Go to http://localhost:4000/practices/ and check the site.

Go to http://localhost:4000/practices/coding/react and http://localhost:4000/practices/coding/code-formatting and check you are redirected to http://localhost:4000/practices/coding/javascript.html.