There is a error message in first use of taos, because the history
file doesn't exist.

This patch tried to create an empty history file after installation,
then users won't see the error message.

| [root@045a9307c53a ~]# taos
|
| Welcome to the TDengine shell from Linux, Client Version:2.0.1.1
| Copyright (c) 2017 by TAOS Data, Inc. All rights reserved.
|
| Failed to open file /root/.taos_history
| taos>
Signed-off-by: Amos Kong <kongjianjun@gmail.com>