(pup-3338) Make systemd the default service provider for SLES 12

OpenSuSE >= 12 and SLES 12 use systemd as the default service management framework. This
updates puppet to use the systemd provider by default on OpenSuSE 12 and 13 and
SLES 12
Merge pull request #3115 from shrug/maint/master/pup-3338

(pup-3338) Make systemd the default service provider for OpenSuSE >= 12 and SLES 12