Generalize with_puppet_running_on method.

Instead of always using pe-httpd as the service name for PE Puppet master, set
that as the default and allow customization on a per-host basis (probably
through Beaker config).

Signed-off-by: Wayne <wayne@puppetlabs.com>
Support optional curl_with_retries behavior.

Specifically, when restarting the puppet master using the initscript/service,
allow per-host configuration to specify whether or not to actually wait for the
puppet master to listen on port 8140 by attemping to grok with. Try up to 120
times at 1-second intervals.

Signed-off-by: Wayne <wayne@puppetlabs.com>