In general, it's not very usuful to repeat the unit name as the description.
Especially when the word is a common name and if somebody doesn't understand
the meaning immediately, they are not going to gain anything from the
repeat either, e.g. "halt", "swap".
In the status-unit-format=combined output parentheses are used around
Description, so avoid using parenthesis in the Description itself.
Replace the very generic cgroup hookup with a much simpler one. With
this change only the high-level cgroup settings remain, the ability to
set arbitrary cgroup attributes is removed, so is support for adding
units to arbitrary cgroup controllers or setting arbitrary paths for
them (especially paths that are different for the various controllers).
This also introduces a new -.slice root slice, that is the parent of
system.slice and friends. This enables easy admin configuration of
root-level cgrouo properties.
This replaces DeviceDeny= by DevicePolicy=, and implicitly adds in
/dev/null, /dev/zero and friends if DeviceAllow= is used (unless this is
turned off by DevicePolicy=).
