Update syntax highlighting of readme.md.
Add custom css additions.
Update part 1.
Update part 2.
Update part 3.
Update part 4.
Add description of basic unix section to index.
Merge branch 'develop'
Create advanced section datafile links.
Add my_first_file.txt link to basic unix.

Change UNIX to Unix in advanced section.
Update the index page.
Add pdf version of tutorial.