Use unittest.mock instead of third party mock

Now that we no longer support py27, we can use the standard library
unittest.mock module instead of the third party mock lib.

Change-Id: I78a70c535950f645fcb3a5f1e820d70cc6958d36
Signed-off-by: Sean McGinnis <sean.mcginnis@gmail.com>

openstack_virtual_baremetal/tests/test_auth.py

@@ -12,9 +12,10 @@
 # License for the specific language governing permissions and limitations
 # under the License.
 
+from unittest import mock
+
 import fixtures
 import json
-import mock
 import testtools
 
 from openstack_virtual_baremetal import auth

openstack_virtual_baremetal/tests/test_build_nodes_json.py

@@ -15,9 +15,9 @@
 import copy
 import json
 import sys
+from unittest import mock
 
 import fixtures
-import mock
 import testtools
 
 from openstack_virtual_baremetal import build_nodes_json

openstack_virtual_baremetal/tests/test_deploy.py

@@ -14,10 +14,10 @@
 # under the License.
 
 import copy
+from unittest import mock
 import unittest
 import yaml
 
-import mock
 import testtools
 
 from openstack_virtual_baremetal import deploy

openstack_virtual_baremetal/tests/test_openstackbmc.py

@@ -13,10 +13,10 @@
 # under the License.
 
 import sys
+from unittest import mock
 import unittest
 
 import fixtures
-import mock
 from novaclient import exceptions
 import testtools
 

test-requirements.txt

@@ -4,7 +4,6 @@ fixtures>=0.3.14
 python-subunit>=0.0.18
 stestr
 testtools>=0.9.36,!=1.2.0
-mock>=1.0
 
 # docs
 sphinx!=1.6.6,>=1.6.2,<2.0.0;python_version=='2.7' # BSD