[Py] Add UT for avg_pooling_3d (#708)

* [Py] Add UT for avg_pooling_3d(Cover uncontigous data input)

python/test/ngraph/test_avg_pooling.py

+# ******************************************************************************
+# Copyright 2018 Intel Corporation
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+# ******************************************************************************
+from __future__ import print_function, division
+
+import numpy as np
+import pytest
+
+import ngraph as ng
+
+
+def test_avg_pooling_3d():
+    manager_name = pytest.config.getoption('backend', default='CPU')
+    rt = ng.runtime(manager_name=manager_name)
+
+    data = np.arange(11, 27, dtype=np.float32)
+    data = data.reshape((1, 1, 4, 4))
+    data = np.broadcast_to(data, (1, 1, 4, 4, 4))
+
+    param = ng.parameter(data.shape)
+
+    avgpool = ng.avg_pool(param,
+                          [2, 2, 2],
+                          [2, 2, 2])
+    comp = rt.computation(avgpool, param)
+    result = comp(data)
+    result_ref = [[[[[13.5, 15.5],
+                     [21.5, 23.5]],
+
+                    [[13.5, 15.5],
+                     [21.5, 23.5]]]]]
+    np.testing.assert_allclose(result, result_ref, rtol=0.001)