install.py: add missing import os.path

Signed-off-by: Danny Al-Gaaf <danny.al-gaaf@bisect.de>
osd.py: replace not existing function call do_list() with disk_list()

Signed-off-by: Danny Al-Gaaf <danny.al-gaaf@bisect.de>
sudo_pushy.py: remove unused imports

Signed-off-by: Danny Al-Gaaf <danny.al-gaaf@bisect.de>
Merge pull request #9 from dalgaaf/wip-da-pylint-2