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 
It reproduces without updating.

1. Remove dhcp.network from cloud-config.yml
1. `sudo rm /etc/systemd/network/dhcp.network`
1. `sudo reboot`
1. CoreOS has no IP.