Fixed#5019 LE cert problem in mirror setups. This patch disables the creation of Let's encrypt SSL certs on mirrored slave servers.

global option to enable pagespeed with nginx - allows to enable pagespeed even if no webserver-config is selected

- typo

- fixed some smaller things in plugins for apache and nginx

Implemented #4271 Creating vHost Website Alias copies default index.html thus breaking the original site if it's based on index.php (or something not index.html)

- Added missing shell escaping

Do not add www as subdomain to a letsencrypt ssl cert when the domain of the webiste is already www.example.com (and not example.com) even if auto subdomain is set to www.