Adapt to the PuppetDB 3.0.0 module changes

This patch fixes helper.rb so that our acceptance tests are compatible with
the new changes in the PuppetDB 3.0.0 module.

Signed-off-by: Ken Barber <ken@bob.sh>
Merge pull request #736 from kbarber/maint/1.5.x/adapt_to_puppetdb_300_mod_changes

Adapt to the PuppetDB 3.0.0 module changes