resource validation logic regarding slash '/'

[wzy816]

In http://wiki.ros.org/Names 1.2.1 it says that "There is at most one forward slash ('/')". It is not double-slash, right?

https://github.com/ros/genmsg/blob/7d8b6ce6f43b6e39ea8261125d270f2d3062356f/src/genmsg/names.py#L131-L132