Fix one typo.
Update session04.rst

I'm not sure about the change on lines 770-771, but it struck me as odd.  And then my suspicion was confirmed on slide 49 (lines 975-6), and the file wsgi_1.py.


Line 1022 says:
You may also want to consider using ``print environ`` in your application so
you can see the dictionary.

But the wsgi_1.py file already has a pprint environ statement in it.
pep8
always hated that green color.  Not worth the slow reveal.
update outline with links to plain html for week 3 and 4
fixing up the assignment folder and presentation for session 04
set up assignment for week 5
re-organized session 5 to build the basic flask app.  login and flash messaging saved for homework
add image of flask helloworld app in browser for session 5 slides
break three portions of the former session 5 lecture out into tutorials to be walked through during the week before session 5
basic starting point for the session 5 flask app.
add slide to take time to fix git with folks
starting to build the session 6 slides
adding the instructions for getting back to a clean master branch for students.
add tutorials to list of stuff for session 4 homework
reorganize session 5&6 reading list to include and emphasize the three tutorials