Add a runner for contrail-test Juniper tests

- add steps in tcp_tests/templates/opencontrail to prepare tests
- add a fixture and a test runner 'test_opencontrail' that gets
  the two variables from environment to pass them to test runner:

  export OPENCONTRAIL_TAGS=smoke
  export OPENCONTRAIL_FEATURES=neutron

- fix docstrings for fixtures
- add print of the environment variables that can be used in tests
  and current defaults (taking into account the exported variables)
diff --git a/tcp_tests/fixtures/opencontrail_fixtures.py b/tcp_tests/fixtures/opencontrail_fixtures.py
new file mode 100644
index 0000000..a00acc7
--- /dev/null
+++ b/tcp_tests/fixtures/opencontrail_fixtures.py
@@ -0,0 +1,32 @@
+#    Copyright 2016 Mirantis, Inc.
+#
+#    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.
+
+
+import pytest
+
+from tcp_tests.managers import opencontrail_manager
+
+
+@pytest.fixture(scope='function')
+def opencontrail(config, underlay, openstack_deployed):
+    """Fixture that provides various actions for OpenContrail
+
+    :param config: fixture provides oslo.config
+    :param underlay: fixture provides underlay manager
+    :rtype: OpenContrailManager
+
+    """
+    return opencontrail_manager.OpenContrailManager(config, underlay,
+                                                    openstack_deployed)
+