Run yamllint on etc/kayobe during pep8 tox env

We run yamllint with the same configuration in kayobe-config, so we
should catch issues here before they are synchronised.

Change-Id: Ia2de07abc7c58040f99766adb950c477800ea56d

.yamllint

+extends: default
+
+rules:
+  braces:
+    max-spaces-inside: 1
+    level: error
+  brackets:
+    max-spaces-inside: 1
+    level: error
+  comments:
+    require-starting-space: false
+  truthy: disable

etc/kayobe/seed-hypervisor.yml

@@ -26,7 +26,8 @@
 # volume group for libvirt storage.
 #seed_hypervisor_lvm_groups:
 
-# Suggested list of seed hypervisor volume groups for libvirt. Not used by default.
+# Suggested list of seed hypervisor volume groups for libvirt. Not used by
+# default.
 #seed_hypervisor_lvm_groups_with_data:
 
 # Seed LVM volume group for data. See mrlesmithjr.manage-lvm role for format.

test-requirements.txt

@@ -13,3 +13,4 @@ oslotest>=1.10.0 # Apache-2.0
 # NOTE(mgoddard): This is required by tools/sphinx8.
 sphinx>=1.5.1 # BSD
 stestr # Apache-2.0
+yamllint # GPLv3

tox.ini

@@ -32,6 +32,7 @@ commands =
   # We use a thin wrapper around doc8 currently, which has support for sphinx
   # directives.
   {toxinidir}/tools/sphinx8 README.rst CONTRIBUTING.rst doc/source --ignore D001
+  yamllint etc/kayobe
 
 [testenv:venv]
 basepython = python3