Ambari service management via standard Linux Systemd service units

Feature Request to port all service management to standard Linux Systemd service units. Ambari can then delegate calls to systemd which is better designed for service management anyway.

This will allow cluster admins to use standard Linux operating system commands, even when Ambari is unavailable (Ambari lacks true native HA at time of writing).

Delegating service management to Systemd improves the design to align with other standard software rather than being more esoteric as Hadoop has historically been (I'm also pushing MapR to do the same and drop their old Warden service management system which is also an outdated mechanism by modern systems engineering standards).