update content based on the current pre-reqs & precourse

[jsms90]

Given our current pre-requisites and pre-course material, some of the content of this tutorial is a bit out of date now. It is a shame to get rid of any content, considering the fact that this tutorial is not aimed exclusively at FAC students:

the first week of the full time Founders & Coders course, or to those just starting out with git

So, @NataliaLKB, I'm not sure how you feel about the suggestions below? But if this is going to be used as the first workshop in the FAC curriculum, it feels a bit strange for students to have any basics explained to them, which we have already required them to cover.

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We now consider the first part of Udacity's git & github course to be mandatory precourse material. So it's probably worth removing the following:

• "Need to Know Terminology" - repo, version control, git & github
• "Why Version Control"
  • "Code Base History" - whole section
• How to install git

We require people to have a github account & to create their own one-page website in order to apply for the course. So we can remove:

• mention of getting a github account for the first time