add(coreos-base/oem-niftycloud): added initial oem for niftycloud

These are the initial oem scripts for niftycloud.
NIFTY Cloud is one of the most popular public cloud service in Japan.

cc: @kelseyhightower 
Ok, if it isn't the different DHCP configuration that is at fault then I suspect that it is actually the restart of networkd that is fixing it, not the config itself. When the system comes up with no IP can you log into the console and run `sudo systemctl restart systemd-networkd.service`? Alternatively in the cloud config:

```yaml
#cloud-config
coreos:
  units:
    - name: systemd-networkd.service
      command: restart
````