Python tweaks

A couple of tweaks to consider.

The super snippet I suppose relies on people using python.el, so having python-info-current-defun available.  Not sure if that's acceptable
About this change just a couple of things, both a superclass and a comment on the class are optional (more so in Python3 for the superclass).

So if we make this way it has to be easy as well to not having to write a superclass and a docstring..

I agree in general that docstrings are good but they are also not always necessary and we end up with this

class Cls(object):
  """
  """
  code..
after which is not very useful..