Improvements from my first attempt at teaching this lesson

[colinsauze]

I have just attempted to teach this lesson for the first time, I only got as far as shell variables in 2.5 hours. But I have fixed a number of issues with the lesson material including:

• Fixes a variety of formatting problems and jekyll snytax issues.
• Adds exercises to man pages, SSH and file transfer
• Swaps lftp for rsync in the file transfer section. This is probably more useful to most researchers on a day to day basis, especially when you already know wget and curl.
• Adding better exercise and teaching timings
• Adding keypoints and questions to most sections

[gdevenyi]

At first glance this looks great, but I still need to go through all of this in detail.

[colinsauze]

no problem, I'm not in rush to get this committed. I might end up teaching part of this again tomorrow, so might have some more improvements after that.