Issue 2999 - Integrate web::server SSL parameters with Hiera

modules/web/manifests/server.pp

 class web::server(
     $vhost,
     $repository,
-    $certificate = hiera('web::server::certificate'),
-    $private_key = hiera('web::server::private_key'),
+    $certificate = hiera('web::server::certificate', 'undef'),
+    $private_key = hiera('web::server::private_key', 'undef'),
     $is_default = false,
     $aliases = undef,
     $custom_config = undef,
     $multiplexer_locations = undef) {
   File {
     owner  => 'root',
     group  => 'root',
     mode   => 0644,
   }
 
   Cron {
     environment => ['MAILTO=admins@adblockplus.org', 'PYTHONPATH=/opt/cms:/opt/sitescripts'],
   }
 
   include nginx
 
   package {['python-jinja2', 'python-markdown']:}
 
   nginx::hostconfig {$vhost:
     content => template('web/site.conf.erb'),
     global_config => template('web/global.conf.erb'),
     is_default => $is_default,
-    certificate => $certificate,
-    private_key => $private_key,
+    certificate => $certificate ? {'undef' => undef, default => $certificate},
+    private_key => $private_key ? {'undef' => undef, default => $private_key},
     log => "access_log_$vhost"
   }
 
   if $multiplexer_locations != undef {
     include spawn-fcgi
     package {'python-flup':}
 
     class {'sitescripts':
       sitescriptsini_source => 'puppet:///modules/web/sitescripts',
     }
@@ skipping 53 matching lines @@
     minute  => '5-55/10',
   }
 
   cron {'update_repo':
     ensure => present,
     command => "hg pull -q -R /home/www/${repository} && python -m cms.bin.generate_static_pages /home/www/${repository} /var/www/${vhost}",
     user => www,
     minute  => '*/10',
   }
 }