py-test: updated to 3.2.4

Pytest 3.2.4:
Bug Fixes
* Fix the bug where running with --pyargs will result in items with empty parent.nodeid if run from a different root directory.
* Fix issue with @pytest.parametrize if argnames was specified as keyword arguments.
* Strip whitespace from marker names when reading them from INI config.
* Show full context of doctest source in the pytest output, if the line number of failed example in the docstring is < 9

(adam)