Lint JJB-yaml files

The yaml-files used to describe the jobs, were not consistently using
whitespaces and single-quotes.

This change lints the yaml files using yamllint, a python-based tool to
lint yaml files. This change also provides a description of how to use
yamllint and a configuration.

Change-Id: I36f8c4982a72cd567fc1035b876db245d80d2a32
diff --git a/jenkins/gerrit-sbt-plugin-template.yaml b/jenkins/gerrit-sbt-plugin-template.yaml
index cf0971d..dee5287 100644
--- a/jenkins/gerrit-sbt-plugin-template.yaml
+++ b/jenkins/gerrit-sbt-plugin-template.yaml
@@ -9,54 +9,48 @@
       - raw:
           xml: <jenkins.plugins.logstash.LogstashBuildWrapper plugin="logstash@1.2.0"/>
     properties:
-       - build-discarder:
-           days-to-keep: 20
-           artifact-days-to-keep: 20
-       - authorization:
-           anonymous:
-             - job-discover
-             - job-read
-             - job-extended-read
+      - build-discarder:
+          days-to-keep: 20
+          artifact-days-to-keep: 20
+      - authorization:
+          anonymous:
+            - job-discover
+            - job-read
+            - job-extended-read
     scm:
       - git:
-         remotes:
-           - origin:
-               url: https://gerrit.googlesource.com/plugins/{name}
-           - gerrit:
-               url: https://gerrit.googlesource.com/gerrit
-         branches:
-           - origin/{branch}
-         submodule:
-           recursive: true
-         skip-tag: true
-
+          remotes:
+            - origin:
+                url: https://gerrit.googlesource.com/plugins/{name}
+            - gerrit:
+                url: https://gerrit.googlesource.com/gerrit
+          branches:
+            - origin/{branch}
+          submodule:
+            recursive: true
+          skip-tag: true
     triggers:
       - pollscm:
           cron: 'H/50 * * * *'
-
     builders:
       - shell:
-         !include-raw: gerrit-sbt-build-branch-plugin.sh
+          !include-raw: gerrit-sbt-build-branch-plugin.sh
     publishers:
       - archive:
-         artifacts: '**/target/**/*{name}*.jar*,**/target/**/*{name}*.json'
-
-    wrappers:
-      - raw:
-          xml: <jenkins.plugins.logstash.LogstashBuildWrapper plugin="logstash@1.2.0"/>
+          artifacts: '**/target/**/*{name}*.jar*,**/target/**/*{name}*.json'
 
 - job-template:
     name: 'plugin-{name}-sbt-{branch}-{gerrit-branch}'
-    description: "Plugin {name} {branch} branch build with Sbt on top of Gerrit {gerrit-branch}\n"
+    description: 'Plugin {name} {branch} branch build with Sbt on top of Gerrit {gerrit-branch}'
     defaults: sbt-build-defaults
     builders:
       - shell:
-         !include-raw: gerrit-sbt-build-branch-plugin.sh
+          !include-raw: gerrit-sbt-build-branch-plugin.sh
 
 - job-template:
     name: 'plugin-{name}-sbt-{branch}'
-    description: "Plugin {name} build with Sbt on top of Gerrit {branch}\n"
+    description: 'Plugin {name} build with Sbt on top of Gerrit {branch}'
     defaults: sbt-build-defaults
     builders:
       - shell:
-         !include-raw: gerrit-sbt-build-plugin.sh
+          !include-raw: gerrit-sbt-build-plugin.sh