Merge branch 'develop' of git.ispconfig.org:ispconfig/ispconfig3 into develop

install/dist/lib/debian60.lib.php

install/dist/lib/fedora.lib.php

install/dist/lib/gentoo.lib.php

install/dist/lib/opensuse.lib.php

install/lib/installer_base.lib.php

install/tpl/debian6_dovecot2.conf.master

install/tpl/debian_dovecot2.conf.master

install/tpl/fedora_dovecot2.conf.master

install/tpl/mysql-virtual_forwardings.cf.master

install/tpl/opensuse_dovecot2.conf.master

server/lib/classes/backup.inc.php

server/plugins-available/apps_vhost_plugin.inc.php

server/plugins-available/mysql_clientdb_plugin.inc.php

server/plugins-available/postfix_server_plugin.inc.php