Update INSTALL.md

I think combining OpenAI, ROS and Gazebo is a brilliant idea. I hope more people can use this repository. The installation is always the first barrier between the users and the framework. I met some problems during the installation, and I notice that most of them have been discussed in issues like #36 and #38, but those solutions are not in the installation instruction. I tested them on Ubuntu 16.04, ROS kinetic, and update the installation instruction of Ubuntu 16.04. But I am not sure if other versions have the same problem. ros-kinetic-ar-track-alvar-msgs is from https://github.com/erlerobot/gym-gazebo/issues/36. Not sure if this happens on Ubuntu 18.04, ROS melodic. The others exist in the installation instruction for Ubuntu 18.04, but they are missed in installation instruction for Ubuntu 16.04.
erlerobot · nzlz · Feb 24, 2019 · Feb 21, 2019 · Feb 21, 2019 · 5902c56cc542b79b2cd5ce10ca5ca3d80af257c9
commit 5902c56cc542b79b2cd5ce10ca5ca3d80af257c9
diff --git a/INSTALL.md b/INSTALL.md
@@ -149,6 +149,8 @@ sudo apt-get install \
 cmake gcc g++ qt4-qmake libqt4-dev \
 libusb-dev libftdi-dev \
 python3-defusedxml python3-vcstool \
+libbluetooth-dev libspnav-dev \
+pyqt4-dev-tools libcwiid-dev \
 ros-kinetic-octomap-msgs        \
 ros-kinetic-joy                 \
 ros-kinetic-geodesy             \
@@ -165,7 +167,8 @@ ros-kinetic-kdl-conversions     \
 ros-kinetic-eigen-conversions   \
 ros-kinetic-tf2-sensor-msgs     \
 ros-kinetic-pcl-ros \
-ros-kinetic-navigation
+ros-kinetic-navigation \
+ros-kinetic-ar-track-alvar-msgs
 ```
 
 ```