[title]
Screen users with superuser privileges

[description]
This check examines the output of command "getent passwd" to identify
user names that run with numerical user ID (UID) 0. These users have
superuser privileges that are conventionally associated with user "root".

Users with UID 0 and the processes started by these users can inadvertently
or maliciously disrupt, damage, manipulate, or destroy a system. Generally,
UID 0 must be assigned sparingly and only to trusted user names.
Security policies often restrict UID 0 to user name "root".

[param trusted_superusers]
A list of user names that are trusted to run as superusers with UID 0.
In the list, the user names are separated by blanks.
