Fixed error in Mail-Backup-Cron-Task (created file /dev/nul - missing l)

Fix for mailrestore, to avoid confusion about web- and mail-backups with same ids

additional added mail_backup to webspace-quota if mail and webdomain are on the same server
changed backup-filesize from formated string to byte-count, because of low-level-remote functions

Falko Timme authored Jan 09, 2015 and Patrick Anders committed Jan 09, 2015

- Made sure SQL backups from servers that differ from the server where the website is on can be restored. A download of the backup is not possible in such a case, therefore I hide the "Download" button.

Conflicts:
	interface/lib/classes/plugin_backuplist.inc.php

Removed possibility of reinstalling Instances

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

see:
- http://git.ispconfig.org/panders/ispconfig3/commit/f7ec00b2f8ba3efc5bdeacef9c813f8a826ae3be#note_454

- 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 HHVM to "Default PHP Handler" field (server configuration).
- Fixed "Unable to load the server configuration from database." error when running server.sh.
- Fixed Javascript (accordions weren't working anymore, directive snippets and other placeholders couldn't be added anymore).

Fixed a Bug in Centos 7 were php-fpm uses sockets while mod_proxy_fcgi in centos 7 does not support that yet.

- Fixed: FS#3710 - Bug with PHP-FPM configuration since 3.0.5.4 Patch 4
- Fixed wrong function calls in system lib.

- Fixed a problem with restart of services due to the fact that Ubuntu has upstart and systemd installed, but only upstart is working without errors.

-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

Use dovecot or maildrop in default-cases
Switching to LMTP and back included in server-postfix-plugin
validator added to disable switching uid-mapping when already created mailusers or in multiserver-environment

Note: The mod_proxy_fcgi that ships with CentOS and Ubuntu does not support sockets yet, so all php-fpm connections are done by IP.