Add YAML linting in check and gate

Introduce YAML linting for check and gate queues so that
we don't introduce incorrect YAML in proposed changes.

Includes a couple of nit fixes so that tests actually pass.

Change-Id: Ie07f11a24fb2ad853b49b69fe295bcae2c5764e6

.gitignore

@@ -0,0 +1 @@
+.tox

.zuul.yaml

@@ -1,3 +1,7 @@
 - project:
-    templates:
-      - noop-jobs
+    check:
+      jobs:
+        - openstack-tox-validate
+    gate:
+      jobs:
+        - openstack-tox-validate

openstack_components.yaml

@@ -548,7 +548,8 @@ tabs:
                 expect to see from the project in the upcoming release.
               title: Horizon - Project Update
             support-teams:
-               i18n: https://governance.openstack.org/tc/reference/projects/i18n.html
+              i18n:
+                https://governance.openstack.org/tc/reference/projects/i18n.html
               documentation:
                 https://governance.openstack.org/tc/reference/projects/documentation.html
 

tox.ini

@@ -0,0 +1,15 @@
+[tox]
+envlist = validate
+minversion = 1.6
+skipsdist = True
+
+[testenv]
+install_command = pip install -U {opts} {packages}
+
+[testenv:validate]
+basepython = python3
+deps =
+    yamllint==1.4.1
+commands =
+    yamllint -f parsable \
+      deployment_tools.yaml openstack_components.yaml sdks.yaml