[FEATURE] Add method to randomize random seed

[ell0ry]

Currently, the random seed seems to be the same (at least inside Docker containers) for scripts that use robowflex with each launch.

So, adding a method that does this would be useful.

[wbthomason]

Does robowflex::RNG::setSeed() not behave as expected? Or do you mean setting a global seed in the environment/similar?