Add SSL cert management to the WebUI

By replacing apache with nginx the latest security features like PFS/HSTS/CSP can be used. In addition nginx requires less resources than apache.

In the same time a SSL management UI must be included to allow the user to upload and manage SSL certificates that can be used by the webserver.
By default a self signed certificate should be created during installation and this should be used by the WebUI. HTTPS should be enabled by default.

I think there should be an option to enable HTTP if the users needs this in his environment. Additional a 'Force HTTPS' option is a nice feature to redirect HTTP calls to HTTPS.