Move test_os_server and apply fixes.

- Add missing meta value for test_create_server
- Add .gitignore for pytest .cache directory

Exclude test_os_server from nose test runs since it was designed
for pytest. The test will work correctly when run using pytest.

This is a temporary issue, as we'll be moving to pytest soon.

test/units/modules/core/cloud/openstack/test_os_server.py

@@ -4,7 +4,7 @@ import yaml
 import inspect
 import collections
 
-from cloud.openstack import os_server
+from ansible.modules.core.cloud.openstack import os_server
 
 
 class AnsibleFail(Exception):
@@ -180,6 +180,8 @@ class TestCreateServer(object):
             flavor: m1.tiny
             nics:
               - net-name: network1
+            meta:
+              - key: value
         '''
         with pytest.raises(AnsibleExit):
             os_server._create_server(self.module, self.cloud)