Implement fix-permissions verb.

- Recursively change ownership of ROS HOME to current user.
 - Fixes: https://github.com/ros-infrastructure/rosdep/issues/332
It is my understanding that if the exception has unicode in it, then it will be coerced into unicode, but that might only be the case when you have unicode literals on. Well, either way it's probably not an issue, this is just a habit I have, we don't have to change it.