Automatic arguments to Python def docstrings

Automatically generates docstrings skeleton for python method arguments.  e.g.

```
def foo(bar, baz=False):
    """
    Keyword Arguments:
     - bar:
     - baz: default: False
    """
```
In response to typing: def<tab>foo<tab>bar, baz=False<tab>

I'm submitting this for review anticipating changes, because:

1.  I have identical lisp in these two snippets.  Is there a way in the context of this repo to avoid this duplication
2.  There are other python snippets which could benefit from this too (```init``` is an obvious one).  If there's a way to resolve #1 I'd like to do that before hitting those
3.  While this is the format example in PEP-257, it's not mandatory.  Could consider other formats, like ":param foo" etc..?

Thoughts?