Use latest velodyne package for organized cloud #508

The organize_cloudoption is able in the master branch of the velodyne package https://github.com/ros-drivers/velodyne/blob/720829573076bf7d7edd4b1de344924fad909049/velodyne_pointcloud/src/conversions/transform.cc#L49-L54 but not in the latest released version.

Having the an organized cloud will allow for more efficient calculation of normals (since there are a known number of "rows" per lidar scan), and provide more information for things like free space projection.

AC: Master branch of velodyne as a git submodule, and the organize_cloud parameter set in the velodyne_lidar.launch file.