The native packages are not required anymore, because the needed
python scripts during compile time are also provided by the
cross-compiled packages and the python scripts are platform
independent. Only the catkin package is provided as native package.
The std-msgs recipe is updated to 0.5.8 to be in line with
4551e7c32d/hydro/release.yaml.
The license string in the package.xml was tuned in 0.5.8 and the
hash of the license string is now the common one.