(QENG-715) Add `install_dev_repo` to Beaker DSL

This is a "push" style method of installing a dev repo from
builds.puppetlabs.lan by first downloading to a directory on the local machine
then pushing to the appropriate configuration directory on the remote machine.

Signed-off-by: Wayne <wayne@puppetlabs.com>
Could we give this a more descriptive name?  We already have a bunch of fetch_puppet_on_OS methods and this could get mixed up in those.