Improved the code that generates the ssh keys for clients and shell users and reorganized it into a central function.

Signed-off-by: Kristián Feldsam <feldsam@gmail.com>

This reverts commit 0b73ad56.

- 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