If the configured log directory does not exist zookeeper will not start. Better to create the directory and start

if the configured log directory does not exists zookeeper will not start. Better to create the directory and start
in zkEnv.sh we can change as follows

if [ "x${ZOO_LOG_DIR}" = "x" ]
then
ZOO_LOG_DIR="."
else
if [ ! -w "$ZOO_LOG_DIR" ] ; then
mkdir -p "$ZOO_LOG_DIR"
fi
fi