Added exit() to Python Intro

Added exit() instruction so participants can be ready to set up the vm
next
organised os x virtualenv instructions

clarified that the command to enter is ‘python3 -m venv myenv’ and that
the ‘myvenv’ can be changed by the user.
myvenv naming clarification

clarified that the user is to change all instances of ‘myvenv’ in the
instructions with the name they chose themselves for their ‘virtualenv’.
timezone

clarified that user should use the country and city they are in for the
timezone settings
reversed order of os x/windows instructions for consistency
clarified that you open files using the code editor
remind user how to use console to open web server
reminder to change 'myvenv' to user name
post.objects.all() changes

clarify parts of instruction text
Merge pull request #94 from JesseIrwin/master

minor changes to python intro and virtualenv instructions