Added stl files of aluminium rails
Modified topic name to 'scan'
Modified minimum distance to circumvent issues observed in gazebo; changed topic name to 'scan'
Modified topic name to 'imu'
Fixed indentation
Modified topic names to be under 'gps/' instead of 'gps_'
Changed update rate as it appears that 30 fps is the maximum gazebo is able to do
xacro:if used to choose whether to load .dae or .stl mesh
Updated xacro file to pass required parameter for choosing which type of mesh to load