register system - doing away with the "New System" pane

Doing away with the "New System" pane in favor of a "Register System"
pane. This pane is much simpler because it only contains two commands to
run on the client system that you want to register.

```bash
rpm -Uvh http://hostname/pub/candlepin-cert-consumer-latest.noarch.rpm
subscription-manager register --org="org_name"
```