use systemd for recent fedora and rhel 7

Although Redhat has largely made <code>chkconfig</code> compatible with <code>systemd</code>, the status function of <code>Chef::Provider::Service::Redhat</code> does not work with newer services, because the only output produced by <code>chkconfig --list</code> is:

```
$ chkconfig --list

Note: This output shows SysV services only and does not include native
      systemd services. SysV configuration data might be overridden by native
      systemd configuration.

      If you want to list systemd services use 'systemctl list-unit-files'.
      To see services enabled on particular target use
      'systemctl list-dependencies [target]'.

netconsole     	0:off	1:off	2:off	3:off	4:off	5:off	6:off
network        	0:off	1:off	2:off	3:off	4:off	5:off	6:off
```

This means that either:

  * Redhat needs to make <code>chkconfig --list</code> fully compatible (not likely)
  * <code>Chef::Provider::Service::Redhat</code> needs to switch to just use <code>chkconfig $service</code>
  * RHEL based platforms that use systemd should switch to using <code>Chef::Provider::Service::Systemd</code>

I'm in favor of the latter, because it will simplify usage of systemd on these platforms, and is not dependent on a backwards-compatibility feature that could some day be dropped. According to [Fedora](https://fedoraproject.org/wiki/Systemd#Does_chkconfig_command_work_with_systemd.3F), their version of <code>systemctl</code> also provides backwards compatibility with <code>chkconfig</code>
ibm_powerkvm and cloudlinux might need this as well, but no idea the version # cutoff there, and think those could be left.  there's also xen and that needs to be left alone and the version #'s there are definitely wrong.  xcp is also weird.  i think i'm okay with leaving all of those out of this PR, unless someone is willing to do the research about which distro versions of those pull in systemd.