Make improvements to the install-guide 

This should prevent errors that students had during the splurty session
I changed the way this works.  It used to be an auto-generated zip file based off github.  Asking users to download a zip file and rename it caused confusion.  Many students didn't rename the folder even though we said to.  I think this also caused some of the students to mess up (and ultimately lead them to run `vagrant init`, which is wrong).

Having us deal with the zip file ourselves adds overhead to us, but removes it from the students.