Systemd runsvdir service overhaul

[otheus]

The service is named runsvdir, not runsvdir-start. The latter was simply a shell script to run the former. The new systemd service file has been renamed to this service and incorporates the functionality of runsvdir-start. Please note, the PATH variable is set via a more canonical method: sbin > bin, and local > usr > /. The PATH that has been set into runsvdir-start was insane.

Relevant to Linux, the OOMKiller is effectively disabled for the runsvdir process. This is quite important.

[imeyer]

I'll get this merged tomorrow, thanks and sorry for the delay.

[davidsainty]

This looks like a reasonable fix for https://github.com/imeyer/runit-rpm/issues/22