Install agents using the frictionless agent install

This change adds logic for installing using the new curlbash style of agent
install. In order to support testing both the old and new styles of install,
we add a new agent role of "frictionless", which indicates that the node
should be installed in the new style. This simply causes it not to download
the PE tarball or generate answer files, and to curl and run a script from the
master (based on the platform tag).