[FEATURE] Support for running a pdns recursor.

[waynegemmell]

Is your feature request related to a problem?

PDNS architecture is ideally two tiers with a recursor reading from an authoritative server. There is no support for the recursor here.
It is mostly doable as it stands by changing the variables but it would be nice to have it supported out of the box.

Describe the solution you'd like

Having a powerdns.recursor sls file that creates a recursor with very little interference would be great.