docstring param format issue

[David Lyle]

When running 'tox -e docs' we get errors like:

/home/david-lyle/django_openstack_auth/openstack_auth/user.py:docstring of openstack_auth.user.User.is_anonymous:5: ERROR: Unknown directive type "param".

.. param:: margin

   A security time margin in seconds before end of an eventual
   authentication.
   Will return ``True`` even if authenticated but that authentication
   ends in less than ``margin`` seconds of time.
   A default margin can be set by the TOKEN_TIMEOUT_MARGIN in the
   django settings.

The formatting used for param is invalid.

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.openstack.org/202222

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/202222
Committed: https://git.openstack.org/cgit/openstack/django_openstack_auth/commit/?id=1524a22dcf4385ccc5091c0bf511a9ed01d45b25
Submitter: Jenkins
Branch: master

commit 1524a22dcf4385ccc5091c0bf511a9ed01d45b25
Author: David Lyle <email address hidden>
Date: Wed Jul 15 12:05:52 2015 -0600

    Fixing docstring formatting for param

    Currently, ''.. param:' is being used. The correct format for sphinx is
    ':param <name>:'

    The current format raises errors when building the docs. This patch
    corrects the formatting and eliminates the errors.

    Closes-Bug: #1474972
    Change-Id: I924f860dfe91c4c785d9c656825c31038072dd07