Fixtures cannot be currently included into other fixtures by using
@pytest.mark.fixtures('fixture_name')
They have to be included as parameters instead.
See bug: https://github.com/pytest-dev/pytest/issues/3664
Also increase the scope of needs_root to the highest, i.e. session, so that it
can be used by any kind of fixture.
Signed-off-by: Joseph Nuthalapati <njoseph@thoughtworks.com>
