Add Zuul to airship-tempest-plugin

This patch set sets up Zuul checks/gating with a simple stestr list
command as a sanity check. Until some other in-flight PSs are merged
no tox commands will run, due to import errors. Merging this to add
Zuul to the project will allow said PSs to get verified +1, and
merged. Afterwards the templates section in .zuul.yaml can be
uncommented to add running py27/py35 unit tests with tox, as well as
pep8.

Change-Id: I8c448c31d6e5b2ca870fa1d2c24c90b68c78a8c6

.zuul.yaml

@@ -0,0 +1,34 @@
+# 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.
+
+- project:
+#    templates:
+#      - openstack-python-jobs
+#      - openstack-python35-jobs
+    check:
+      jobs:
+        - stestr-list
+    gate:
+      jobs:
+        - stestr-list
+
+- nodeset:
+    name: airship-tempest-plugin-single-node
+    nodes:
+      - name: primary
+        label: ubuntu-xenial
+
+- job:
+    name: stestr-list
+    description: Sanity check to make sure stestr can list tests
+    nodeset: airship-tempest-plugin-single-node
+    run: tools/gate/playbooks/stestr-list.yaml

tools/gate/playbooks/stestr-list.yaml

@@ -0,0 +1,8 @@
+- hosts: primary
+  tasks:
+    - name: Run stestr list as a sanity check
+      shell: |
+        set -xe;
+        ./tools/gate/scripts/stestr_list.sh
+      args:
+        chdir: "{{ zuul.project.src_dir }}"

tools/gate/scripts/stestr_list.sh

@@ -0,0 +1,17 @@
+#!/bin/bash
+
+# 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.
+
+set -xe
+pip install stestr
+stestr --test-path ./airship_tempest_plugin/tests/unit list