Add puppetdb to a new puppetdb host

This brings in the puppetdb module via install_modules.sh and
creates a new class, openstack_project::puppetdb. It was modeled
on openstack_project::puppetmaster. Note that this will not enable
puppetdb to participate in the Puppet ecosystem yet. An additional
class will have to be added to the master:

  class { 'puppetdb::master::config':
    puppetdb_server => 'puppetdb',
  }

I will leave this out of this change so we can bring up puppetdb in
stages.

This paves the way for puppetboard to be brought online.

Change-Id: I8194372bd31e08f12a815fd04dcdf338565ed911
Merge "Add puppetdb to a new puppetdb host"