your script seems to be interesting. I don't know ~anything about Python but somehow I managed to install and setup everything that this script needs. I am able to use functions like print ADL.getTemp() from ADK successfully.
If I try the crontab's first new line, DISPLAY=:0.0 python save_stats.py, manually in terminal I only get this:
File "save_stats.py", line 8
SyntaxError: invalid syntax
everything else seems to be working, your script creates .csv-files under /var/www/stats/ correctly etc.
Anyone have a guess on the possible problem? I hate to be so close for working stats