Use brokers in Windows installs

In order to have operational Powershell brokers in Windows, proper hooks need
to be in place to download and execute the file right before the user is
able to log into the system. This commit achieves that by having
the Windows installer download the file from the server and register a
service to run the file on boot.

Included in this commit are translations of the no-op broker and the PE
broker. The latter requires a valid URL to the puppet agent MSI, which is
either derived from the `version` parameter, or supplied directly by the
broker's config.

Fixes https://tickets.puppetlabs.com/browse/RAZOR-59