Synchronize time in puppet broker

Per https://github.com/puppetlabs/razor-server/pull/276:

Without running ntpdate before registering with the puppet master, sometimes, the agent can't retrieve a catalog with an error that says the certificate is not yet valid.

ntpdate should run before the puppet or puppet-pe brokers communicate with the master if the ntpdate_server config is supplied.

To make this as generic as possible, both brokers should include a new, optional ntpdate_server config that defaults to not running ntpdate. We assume that many users will already have ntpdate configured on their network.

In Scope

• Update the puppet and puppet-pe brokers to synchronize the time before installing the agent.
• Add a ntpdate_server config with the above default to the configuration.yaml of each broker.