Issue 3062 - Explicitly ensure user "nginx" is present

modules/notificationserver/manifests/init.pp

 class notificationserver($is_default = false) {
   if !defined(Class['nginx']) {
     class {'nginx':
       worker_connections => 4000,
       ssl_session_cache => off,
     }
   }
 
   class {'sitescripts':
     sitescriptsini_source => 'puppet:///modules/notificationserver/sitescripts.ini'
   }
 
   exec {'fetch_notifications':
     command => 'hg clone --noupdate https://hg.adblockplus.org/notifications /opt/notifications && chown -R nginx /opt/notifications',
     path => ['/usr/bin/', '/bin/'],
     require => [
       Package['mercurial'],
-      Package['nginx'],
+      User['nginx'],
     ],
     onlyif => 'test ! -d /opt/notifications'
   }
 
   cron {'update_notifications':
     command => 'hg pull -q -u -R /opt/notifications',
     environment => ['MAILTO=admins@adblockplus.org,root'],
     minute => '*/5',
     user => 'nginx',
     require => Exec['fetch_notifications'],
@@ skipping 25 matching lines @@
   nginx::hostconfig{'notification.adblockplus.org':
     source => 'puppet:///modules/notificationserver/site.conf',
     global_config => template('notificationserver/global.conf.erb'),
     is_default => $is_default,
     certificate => 'easylist-downloads.adblockplus.org_sslcert.pem',
     private_key => 'easylist-downloads.adblockplus.org_sslcert.key',
     log => 'access_log_notification',
     log_format => 'notification',
   }
 }