Robot model is not displayed in gzweb

[mmurooka]

I changed the way to add robot to gazebo in #133.
Now robot model is added by spawn node in launch file.
https://github.com/start-jsk/rtmros_gazebo/blob/master/hrpsys_gazebo_general/launch/gazebo_robot_no_controllers.launch#L52-L54

In this case, gzweb can not display robot model in browser.
turtlebot is also using the same way, and the same problem occurs.
https://bitbucket.org/osrf/gzweb/issue/45/creating-local-model-of

[mmurooka]

以下でうまくいくはずに思うのですがダメでした．
以下をマージしてもらった後で，これで上手くいかない理由をgzwebのリポジトリにIssue切って聞いてみます．
#139
start-jsk/rtmros_tutorials#91