Lint YAML files

Currently most OpenStack code is linted, but YAML files are not.
This patch enables linting in tox tests using the yamllint tool [1].

It also corrects some indentation misalignments and a line longer
than 80 chars; the new CI test will prevent new errors from coming in.

[1]: http://yamllint.readthedocs.org/

Change-Id: Ie33e2636be97a09f27e519be185382be82fa19f2

reference/projects.yaml

@@ -2731,7 +2731,8 @@ Packaging-deb:
     irc: zigo
     email: zigo@debian.org
   mission: >
-     Maintain packages for Debian (and other deb based distributions) as a community.
+    Maintain packages for Debian (and other deb based distributions) as a
+    community.
   tags:
     - team:single-vendor
   deliverables:

test-requirements.txt

@@ -2,4 +2,5 @@
 sphinx>=1.1.2,!=1.2.0,<1.3
 oslosphinx>=2.2.0  # Apache-2.0
 PyYAML>=3.1.0
+yamllint>=0.5.2
 requests-cache

tox.ini

@@ -18,3 +18,4 @@ commands = python setup.py build_sphinx
 
 [testenv:validate]
 commands = python tools/validate_tags.py
+           yamllint .