detect the ubuntu version based on /etc/os-release

Uwe Merbeth

2016-05-09 f5daecadf5846ff0b2d512e6a1a47f17342fe02b

1
ALTER TABLE `mail_user` ADD `disablesieve-filter` ENUM( 'y', 'n' ) NOT NULL DEFAULT 'n' AFTER `disablesieve`;