We are using Unity 2017.2.
These commands will handle updating of the ROS submodules. Run them from the top directory of the project using git bash.
git submodule update --init
cd Assets/ROSBridgeLib
git reset --hard HEAD
printf '[submodule "Pointcloud"]\n\tpath = Pointcloud\n\turl = https://github.com/srv/Pointcloud.git'>.gitmodules
git submodule sync
git submodule update --init