As described in this bug https://bugs.launchpad.net/fuel/+bug/1459252
slow connection to ubuntu mirror can lead to errors. Lets try choose
mirror which is near build server.
Change-Id: I7a367cbb6edbcf30dceb52934a9adf35cbd7ce5a Signed-off-by: Michal Skalski <mskalski@mirantis.com>