title: Pytest setup/teardown hooks for session
body: <p><code>Pytest</code> <a href="http://doc.pytest.org/en/latest/xunit_setup.html" rel="noreferrer">has</a> <code>setup and teardowns</code> hooks for <code>module, class, method</code>.</p>
  
  <p>I want to create my custom test environment in setup (before start of test session) and cleanup after all tests will be finished.
  In other words, how can I use hooks like <code>setup_session and teardown_session</code>?</p>