move questions back and do some auto-filling
add questions for 07
readings from email
shuffling questions around
finish clearing out `sklearn`; closes #171
remove repeated link
move viz task out; refs #25
extract pitch assign; closes #25

The project assignment still have to be assigned in sensible places, of
course.
split sklearn walkthrough numpy/pandas parts
clean up a little
update exercises for new flow
Merge pull request #175 from ajschumacher/python2

re-organize, close issues, update python day 2