Bug#960593: hplip: Requires login as root instead of as user

[Teemu Ikonen <tpikonen@gmail.com>]

Note that this bug can be mitigated by adding the two lines below to 
~/.hplip/hplip.conf:

-*-
[authentication]
su_sudo=sudo
-*-

This is no excuse for the code in base/password.py which should be 
fixed to something sane, like checking for users sudo permissions and 
using sudo if it works, instead of relying on a fixed value per OS.