Use getpwnam before getpwuid since two users with same uids can exists
(affects new login classes code only)
The same fixes as in inetd: by default run `system crontab things' with
daemon login class now, not restrict them to user class breaking
compatibility with old way (so-called nobody limits problem)
Implement user[:group][/login-class] syntax in system crontab
for more flexible control (the same as in inetd)
