forbid writes and reads to the root cgroup or cuttr's cgroups

Change in the check_path interface: there are now two different methods,
check_file and check_dir.
check_dir is the previous check_path.
check_file checks that the file is not inside a root cgroup and it also
checks that it is not in one of cuttr's cgroups. This is to make sure
that a user cannot make any changes to the values which are not his.
2 jobs for master in 2 minutes and 25 seconds (queued for 1 second)
Name Stage Failure
failed
style:check Test
         .encoder(Box::new(PatternEncoder::new(
"[{d(%Y-%m-%d %H:%M:%S)}] {h({l:10.10})}: {m}{n}",
- ))).target(Target::Stderr)
+ )))
+ .target(Target::Stderr)
.build();

let config = Config::builder()
ERROR: Job failed: exit status 1