Remove cert->httpd notify when Passenger is disabled

Dependent Service[httpd] resource is missing in the non-Passenger case.

Fixes GH-183
Add support for puppetserver

Set server_implementation to 'puppetserver', which will disable Passenger,
install puppetserver and start it as a standalone service.
Don't manage puppetmaster/puppetserver services that aren't present

Under Debian or Ubuntu, the Puppet service providers throw errors for unknown
services, so just leave them unmanaged by default.
Reword site.pp message to prevent confusion
Update puppetmaster vhost TLS settings

This solves part of issue #5900. The settings are copied from
https://github.com/puppetlabs/puppet/commit/214c526