- added cron for letsencrypt renewal

- backported patches

see:
- http://git.ispconfig.org/panders/ispconfig3/commit/f7ec00b2f8ba3efc5bdeacef9c813f8a826ae3be#note_455

- http://en.wikipedia.org/wiki/SPDY

- Directive snippets can now be made available to clients; clients can select an available directive snippet for a website - the appropriate snippet will then be written to the vhost configuration file. This is useful for example on nginx where clients have no access to the Options tab of a website.

-Added a new option "Network Filesystem" under System > Server config > Web to toggle on / off the _netdev option for the bind mounts in /etc/fstab

Revert "Fixed: FS#3581 - Website unaccessible under some circumstances when using seo redirection *.domain to www.domain"

This reverts commit 5742e4c9.

Fixed: FS#3581 - Website unaccessible under some circumstances when using seo redirection *.domain to www.domain
(only for apache2, nginx still to do)

Changed web folder permissions in nginx setups from 711 to 751 to avoid (false) permissions warnings in log files.

- Fixed FS#3366 - Certain Custom php.ini settings seem to be stripped before being saved to .conf file.