Rework reboot/shutdown/poweroff/halt command

Rework reboot/shutdown/poweroff/halt command

The provided utilities did not support all cases in which reboot and similar
utilities needs to support, ie.
 - running when dbus service is not running (eg. in upgrade target)
 - being invoked from vip handler when system must reboot immediately

This commit drops deviced custom tools - systemd native tools should be used
instead.

To ensure deviced is used during shutdown following is added:

 - deviced-request-shutdown utility and related service files

   These are installed as dependencies of systemd-standard shutdown
   procedure, causing these to be pulled automatically.

   Separate utility is added as, eg. dbus-send might not be available on
   production images.

 - /run/systemd/reboot-param handling is added

   This file is written by standard systemd reboot tool, so we need to both
   + read this file for reboot param in deviced-shutdown (needed if deviced was not used during shutdown)
   + read this file for deviced PowerOff argument (needed for normal operation)

Change-Id: Ic013e6fa1f4848a17abc025cf99cffeea9916542