(PUP-2010) have test repos pushed to hosts during acceptance testing

This patch changes the logic of how test packages are installed on SUTs.
Currently, repo packages are pulled by the individual SUTs - this works
because we assume that the SUTs are located within the Puppet Labs
network and can access builds.puppetlabs.lan. To run acceptance tests
in the cloud the workflow needs to be changed to have the test packages
pushed to the SUTs by the jenkins master node.

Tested successfully on jenkins, also updated spec tests.

This code relies on Beaker 1.8+ DSL methods.
Merge pull request #2456 from anodelman/stable

(PUP-2010) have test repos pushed to hosts during acceptance testing