Use the first network interface only.
Use the first network interface only.

This allows the script to work on machines with multiple interfaces
defined. This is common when running on VirtualBox and a host-only
interface is added to SSH into.

Fixes #TRAINVM-139

marrero984/education-builds,carthik/puppetlabs-training-bootstrap,joshsamuelson/puppetlabs-training-bootstrap,petems/puppetlabs-training-bootstrap,samuelson/education-builds,samuelson/education-builds,marrero984/education-builds,samuelson/puppetlabs-training-bootstrap,carthik/puppetlabs-training-bootstrap,samuelson/puppetlabs-training-bootstrap,kjhenner/puppetlabs-training-bootstrap,joshsamuelson/puppetlabs-training-bootstrap,johnduarte/puppetlabs-training-bootstrap,carthik/puppetlabs-training-bootstrap,puppetlabs/puppetlabs-training-bootstrap,puppetlabs/puppetlabs-training-bootstrap,samuelson/education-builds,kjhenner/puppetlabs-training-bootstrap,wbhamilton/puppetlabs-training-bootstrap,klynton/puppetlabs-training-bootstrap,johnduarte/puppetlabs-training-bootstrap,klynton/puppetlabs-training-bootstrap,joshsamuelson/puppetlabs-training-bootstrap,wbhamilton/puppetlabs-training-bootstrap,klynton/puppetlabs-training-bootstrap,puppetlabs/puppetlabs-training-bootstrap,kjhenner/puppetlabs-training-bootstrap,wbhamilton/puppetlabs-training-bootstrap,johnduarte/puppetlabs-training-bootstrap,marrero984/education-builds,samuelson/puppetlabs-training-bootstrap,petems/puppetlabs-training-bootstrap,petems/puppetlabs-training-bootstrap