Add agent tarball caching and other jazz

* makes simplified install work for all roles in the classroom
    * currently requires network to set up initially
    * clearly the master still needs the full installer
    * see https://tickets.puppetlabs.com/browse/TRAINVM-149
* also updates PE 3.7 support again
    * spaceship hack will be needed on release
    * session-timeout management will not make release
* remove `pe-console-services` and `pe-puppetserver` notifies
    * manual restart is required post classification
    * see https://tickets.puppetlabs.com/browse/TK-78