More automated configuration with Puppet

octocatalog-diff was designed to run in a CI environment where there is no Puppet master or even Puppet agent available. Still, in many cases there *is* a Puppet configuration. To make things easier to configure, we should give the ability to read a Puppet master or agent configuration in lieu of setting up those parameters in octocatalog-diff.

Some things we might be able to get from the agent or server configuration:
- Path to ENC
- Path to global hiera.yaml
- Use a Puppet agent that's already installed
- Code path for checked out code
- SSL certificates to connect to Puppet master or puppetdb
- IP and port for the Puppet master