docs: fix the incompatible demo_1.5.bag, stored it by online link.

README.md

@@ -57,7 +57,8 @@ to load Dreamview UI.
 ```
 # in a different terminal, in the apollo directory
 bash docker/scripts/dev_into.sh # jump into the docker container
-rosbag play -l ./docs/demo_guide/demo_1.5.bag
+bash ./docs/demo_guide/rosbag_helper.sh download # download rosbag
+rosbag play -l ./docs/demo_guide/demo_1.5.np.bag
 ```
 Dreamview should show a running vehicle with trajectory now.
 ![Dreamview with Trajectory](docs/demo_guide/images/dv_trajectory_1.5.png)

docs/demo_guide/README.md

@@ -22,6 +22,9 @@ Setup steps:
 
     ```
     rosbag play docs/demo_guide/demo.bag --loop
+    # or 
+    bash docs/demo_guide/rosbag_helper.sh download #download rosbag
+    rosbag play docs/demo_guide/demo_1.5.np.bag --loop
     ```
 
     The `--loop` option enables rosbag to keep playing the bag in a loop playback mode.

docs/demo_guide/README_cn.md

@@ -22,6 +22,9 @@ Apollo演示的安装步骤：
 
     ```
     rosbag play docs/demo_guide/demo.bag --loop
+    # 或者
+    bash docs/demo_guide/rosbag_helper.sh download # 下载rosbag
+    rosbag play docs/demo_guide/demo_1.5.np.bag --loop
     ```
 
     选项 `--loop` 用于设置循环回放模式.

docs/demo_guide/rosbag_helper.sh

+#!/usr/bin/env bash
+
+###############################################################################
+# Copyright 2017 The Apollo Authors. All Rights Reserved.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+# http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+###############################################################################
+
+
+DIR="$( cd "$( dirname "${BASH_SOURCE[0]}" )" && pwd )"
+cd "${DIR}"
+
+DEMO_BAG_URL="https://github.com/ApolloAuto/apollo/releases/download/v1.5.0/demo_1.5.np.bag";
+
+function print_usage() {
+    echo "bash rosbag_helper.sh download: retrieve rosbag file from remote"
+}
+
+function main() {
+    local cmd=$1
+    shift
+    case $cmd in
+        download)
+            wget -v $DEMO_BAG_URL -O demo_1.5.np.bag
+            ;;
+            *)
+            print_usage
+            ;;
+    esac
+}
+
+main $@