update puppet-enterprise.sh to install 3.1 agents
update puppet-enterprise.sh to install 3.1 agents

uses current install method for PE 3.1, downloads either redhat or
debian 7 64bit tarballs, unpacks, and passes an generic answers file.

ihmccreery/puppetlabs-gce_compute,icg-puppet/puppetlabs-gce_compute,hunner/puppetlabs-gce_compute,puppetlabs/puppetlabs-gce_compute,icg-puppet/puppetlabs-gce_compute,hunner/puppetlabs-gce_compute,GoogleCloudPlatform/puppetlabs-gce_compute,ihmccreery/puppetlabs-gce_compute,puppetlabs/puppetlabs-gce_compute,GoogleCloudPlatform/puppetlabs-gce_compute