Merge pull request #191 from bulwahn/collada-urdf

recipes for collada-urdf
pcl: initial commit (resolves #135)

Based on initial work by bulwahn: https://github.com/bulwahn/meta-ros/tree/pcl-v4
Extensively discussed at #135
Merge pull request #186 from KristofRobot/pcl-v6

pcl: initial commit (resolves #135)
eigen-conversions: initial commit
geometry-experimental: initial commit
packagegroup-ros-world: adding new recipes
README.md: acknowledge Kristof's contributions