Request to add a License file

[IanTheEngineer]

According the package.xml files wsg_50_simulation, wsg_50_common, wsg_50_driver, this code is licensed "BSD". The original Google Code Archive has that version listed as BSD-3.0 Clause.

Would you consider adding a the appropriate LICENSE text file either at the top level of the repo, or in the packages themselves to make the licensing clear for this code? That would come with the side benefit of Github automatically rendering a link to the license in the sidebar and making this repo searchable under that license. Thanks!