Handle deprecation of inspect.getargspec
Handle deprecation of inspect.getargspec

The getargspec function is deprecated in python3 and in some cases the
deprecation warning can actually cause unit test failures[1]. Follow
Sean's example[2] to smartly use the right inspect function and avoid
deprecation warnings.

[1] http://logs.openstack.org/47/524747/3/check/openstack-tox-py35/1585cb9/testr_results.html.gz
[2] https://review.openstack.org/#/c/521979/

Change-Id: Ia0ac9a79f9faf618aeafae4621afaf1db62ed1e5

openstack/keystone,openstack/keystone,mahak/keystone,mahak/keystone,mahak/keystone,openstack/keystone