Merge branch 'stable-3.1'

TODO.txt

install/lib/installer_base.lib.php

install/lib/update.lib.php

install/uninstall.php

interface/lib/classes/validate_server.inc.php

interface/web/admin/form/server_ip.tform.php

interface/web/admin/form/server_ip_map.tform.php

server/plugins-available/apache2_plugin.inc.php

server/plugins-available/network_settings_plugin.inc.php

server/plugins-available/nginx_plugin.inc.php