Add Custom FCCT Config Option to ignition_sets

[kenmoini]

So get this...use Pilot Light for a self-assembling environment based on DNS.
Add an extra custom_fcct_config key to the ignition_sets - include fcct into the functions of the program.
Then, pass that key to a file, fcct it up to ignition, serve OpenShift and custom CoreOS workloads assembled from Pilot Light.

A great example of this would be for the Pilot Light server itself, or HAProxy and DNS. This would speed up provisioning of complex OpenShift environments, like the ones driven into IBM Cloud via RHPDS.