Added Major Release Case Switch For Run Ressource

Dear all,

on centos 7 or rhel 7 i would appreciate to use the systemd service files.
I added a case switch for rhel / centos 7 to use the archlinux systemd files.
For me it is working as expected and my travis job runned well.
https://travis-ci.org/hingstarne/garethr-docker/builds/40001509
Cheers