Path.contains_points() incorrect return

`Path.contains_points()` returns an array with all elements `False` if one element should be `False`.

Example:
```python
from matplotlib.path import Path
import matplotlib.patches as patches

vertices = [(2., 2.), (2., 5.), (6., 5.), (6., 2.), (2., 2.)]
codes = [Path.MOVETO, Path.LINETO,
         Path.LINETO, Path.LINETO, Path.CLOSEPOLY]
path = Path(vertices, codes)

path.contains_points([[3, 3]])
>>> array([ True], dtype=bool)

path.contains_points([[3, 3], [0, 0]])
>>> array([False, False], dtype=bool)
```
The deprecated `nxutils.points_inside_poly` produces the correct result:
```python
from matplotlib.nxutils import points_inside_poly
points_inside_poly([[3, 3], [0, 0]], vertices)
>>> array([ True, False], dtype=bool)
```

The `contains_points` docstring is also the same as `contains_point`

This is using the current master