Allow full path for library exceptions.

[Dreamsorcerer]

It would be preferable to be able to use the full path e.g. aiohttp.web.HTTPException in an example such as:

from aiohttp import web
def foo():
    """
    Raises:
        aiohttp.web.HTTPException
    """
    raise web.HTTPException

Currently, it only allows web.HTTPException to appear in the docstring.

If it's too tricky to get the import name, how about allowing a partial match?

e.g. It's currently matching web.HTTPException, so it would be fine if it matched anything ending in that, i.e. docstring_exception.endswith("web.HTTPException").

I guess it wouldn't help with as imports, but probably good enough most of the time.

[jtpavlock]

This also occurs if just importing the base name

import mediafile

def foo():
    """
    Raises:
        mediafile.UnreadableFileError
    """
    raise mediafile.UnreadableFileError

Does not work. Instead you must specify the abbreviated exception name:

def foo():
    """
    Raises:
        UnreadableFileError
    """
    raise mediafile.UnreadableFileError

[pawamoy]

Related to #9