Don't use Debian's httpredir for backports (#5392)

Hopefully this solves https://github.com/home-assistant/home-assistant/pull/5322#issuecomment-273041585

script/setup_docker_prereqs

@@ -35,7 +35,7 @@ echo "deb http://download.telldus.com/debian/ stable main" >> /etc/apt/sources.l
 wget -qO - http://download.telldus.se/debian/telldus-public.key | apt-key add -
 
 # Add jessie-backports
-echo "deb http://httpredir.debian.org/debian jessie-backports main" >> /etc/apt/sources.list
+echo "deb http://deb.debian.org/debian jessie-backports main" >> /etc/apt/sources.list
 
 # Install packages
 apt-get update