improving dependencies in the python recipes; simplifying core-image-ros after dependencies are improved

adding dateutil to the image, as i do not know why RDEPENDS does not ensure that dateutil exists in the rootfs

tried to add python-vcstools via dependency in python-rosinstall but it does not do and then added it the core-image instead; tuned layout and order in core-image

adding the recipe python-vcstools, as now that the python recipes do not use setuptools to get all the dependencies write we need further recipes

adding the setuptools class from openembedded classic; adjusting the packages; adding legal statement