Removed comments and other junk

Some comments and old code that was unescessary was removed from
GitPrimer.tex
Changed structure of sections

I changed the order of the sections so that the git demo is
independent of GitHub.  This was done so that the audience doesn't
confuse the two, or think that GitHub is somehow necessary for VC.
Now the sections are as follows:

git
git demo
GitHub
GitHub demo
Learn More
Change 'Demonstration' to 'Demo'

Changed two instances in the section titles.
Edited Collaboration/Requirements slide

Also added a slide to the "Incorporate into Repository" series of slides.
Edited "Incorporate into Repository" section

To be honest it is a little difficult to describe changes to slides in
the commit log.  With code it is more natural.  But until the
revisions to the presentation become small it is hard to be more
specific than "Edited such and such."  It would be crazy to list each
typo that was fixed, or grammar that was clarified.  Even if it is
less useful than commit logs associated with code we must still try to
maintain a useful record of the changes to the slides.