[BUG] Unused code in /tmp

Created by: LuisAlejandro

Hello,

Upon inspection at the odoo-80-image i've found that the /tmp is not clean after finishing the image, resulting in an extra +660MB.

$ docker run -it vauxoo/odoo-80-image bash
root@e753f32b21ce:/# du -hs /*
6.3M    /bin
4.0K    /boot
0   /dev
3.8M    /etc
4.0K    /home
24M /lib
4.0K    /lib64
4.0K    /media
4.0K    /mnt
4.0K    /opt
0   /proc
7.3M    /root
44K /run
6.8M    /sbin
4.0K    /srv
0   /sys
663M    /tmp           <<<<<<<<<
921M    /usr
16M /var

I'll be making a PR soon.