Set visualvm.display.name in JVMFLAGS

Signed-off-by: Maxime Petazzoni <max@signalfuse.com>
upgrade zookeeper to release 3.4.6
disable logstash logging, added log4j.properties
workaround for ZOOKEEPER-1711
console log level raised to INFO
use logging instead of `print`
use yandex/ubuntu as base image