Added 'k8s_deployed' fixture

Created a separate fixture for Kubernetes deployment.
Modified existing k8s related fixtures / tests so they
use it now and updated templates with k8s environments.

Also this patch includes few minor changes:

 * removed unused fixture 'deploy_openstack' which
   was a full copy of 'openstack_deployed' fixture;
 * removed unused modules imports;
 * fixed typos and docstrings.

Change-Id: Ic35551f3e52913cede753b92e7d5a81f54570b01
Reviewed-on: https://review.gerrithub.io/365234
Reviewed-by: <vrovachev@mirantis.com>
Reviewed-by: Dennis Dmitriev <dis.xcom@gmail.com>
Tested-by: Tatyanka Leontovich <tleontovich@mirantis.com>
diff --git a/tcp_tests/tests/system/conftest.py b/tcp_tests/tests/system/conftest.py
index 89dfc3d..015c7ed 100644
--- a/tcp_tests/tests/system/conftest.py
+++ b/tcp_tests/tests/system/conftest.py
@@ -24,6 +24,7 @@
 from tcp_tests.fixtures.stacklight_fixtures import *
 from tcp_tests.fixtures.virtlet_fixtures import *
 from tcp_tests.fixtures.virtlet_ceph_fixtures import *
+from tcp_tests.fixtures.k8s_fixtures import *
 
 
 __all__ = sorted([  # sort for documentation
@@ -52,6 +53,9 @@
     # stacklight_fixtures
     'sl_actions',
     'sl_deployed',
+    # k8s fixtures
+    'k8s_actions',
+    'k8s_deployed',
     'virtlet_actions',
     'virtlet_deployed',
     'virtlet_ceph_actions',