Feature: Configure agents using SRV records
Created by: aaron-miller
This PR includes the ability to configure the following settings in puppet.conf:
- use_srv_records
- srv_domain
- pluginsource
- pluginfactsource
This is useful for teams that want to use the SRV lookups for Puppetmaster lists. It also changes some logic for a few settings to make transitioning from defined Puppetmasters to SRV records.