Fix RHEL pre 7 provider service mapping

This is to fix the issue made when the Redhat-based 7 distro
support was added.

Steps to reproduce:
* add a cookbook recipe that starts a service, e.g. nginx
* run chef

Expected
* nginx to be started and reboot enabled

Actual

    ==> test6: [2014-09-27T12:41:48+00:00] ERROR: service[nginx] (nginx::package line 46) had an error: Errno::ENOENT: No such file or directory - /bin/systemctl is-active nginx --quiet
    ==> test6: [2014-09-27T12:41:48+00:00] FATAL: Chef::Exceptions::ChildConvergeError: Chef run process exited unsuccessfully (exit code 1)