target: don't synthesize a runlevel property for targets anymore since we don't need it anymore and it is crutfy

audit,utmp: implement audit logic and rip utmp stuff out of the main daemon and into a helper binary

This makes it easier to support /etc/sysconfig/xxxx with command line
env vars in style of $OPTIONS which might or might not be set.

Some unit shall never be start on user request (e.g. shutdown.target)
others never be stopped on user request (e.g. auditd.servce), hence
offer options for both.

https://bugzilla.redhat.com/show_bug.cgi?id=619922

manager: when two pending jobs conflict, keep the one that "conflicts", remove the one that is "conflicted"

This gives the writer of units control which unit is kept and which is
stopped when two units conflict.

Previously we checked the SysV priority value to figure out if a SysV
unit was enabled or not, since th value was mostly read from the S
startup links. Since we read this value from the LSB headers as a
fallback we hence ended up considering a lot more services enabled than
were actually enabled.

This patch adds an explicit boolean which encodes whether a sysv service
is enabled or not via S links.

https://bugzilla.redhat.com/show_bug.cgi?id=615293

Fixes an assertion triggerable via D-Bus.

https://bugzilla.redhat.com/show_bug.cgi?id=622008

"systemctl dot" has been broken since the addition of the "Following="
property.