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 
like this?

```
${VMTOOLSD} --cmd 'info-get guestinfo.user_data' | openssl enc -d -base64 | coreos-cloudinit --from-stdin
```