Update magit commit mode hook

They now use git-commit-mode (used to use magit-log-edit)
Add org babel python output fix

I was having two issues with python output from org babel (both when
results were set to output, not value)

1. python shell characters (>>> and ...) were making their way into the
   output
2. Meaningful spaces (such as those in front of data frame column names)
   were getting eaten

This is a temporary fix that seems to solve this. I should post to the
org mode list and see if others have these issues.