yamllint: Make all files in awx pass yamllint

This commit updates all files that weren't passing yamllint for them to
pass.

A new yamllint target has been added. One can run `tox -e yamllint` or
`yamllint -s .` locally to ensure yaml files are still passing.

This check will be enabled in the CI so it can get on every new
contributions, and prevent merging non-compliant code.

Signed-off-by: Yanis Guenane <yguenane@redhat.com>

tools/elastic/docker-compose.elastic-override.yml

@@ -1,3 +1,4 @@
+---
 # Structure for the Elastic Stack docker configuration came from docker-elk:
 # https://github.com/deviantony/docker-elk
 # docker-elk is under the MIT License,
@@ -15,8 +16,8 @@ services:
       - "9300:9300"
     environment:
       ES_JAVA_OPTS: "-Xms1g -Xmx1g"
-    # networks: # add back in when a connection to tower_tools is possible
-    #   - docker_elk
+      # networks: # add back in when a connection to tower_tools is possible
+      #   - docker_elk
 
   logstash:
     build: elastic/logstash/

tools/elastic/docker-compose.logstash-link-cluster.yml

@@ -1,3 +1,4 @@
+---
 version: '2'
 services:
   # Tower Development Cluster
@@ -9,4 +10,4 @@ services:
       - logstash
   tower_3:
     links:
-      - logstash
+      - logstash

tools/elastic/docker-compose.logstash-link.yml

@@ -1,3 +1,4 @@
+---
 version: '2'
 services:
   # Primary Tower Development Container

tools/elastic/kibana/config/kibana.yml

@@ -1,3 +1,4 @@
+---
 # Kibana is served by a back end server. This setting specifies the port to use.
 server.port: 5601
 
@@ -89,4 +90,4 @@ elasticsearch.url: "http://elasticsearch:9200"
 
 # Set the interval in milliseconds to sample system and process performance
 # metrics. Minimum is 100ms. Defaults to 10000.
-# ops.interval: 10000
+# ops.interval: 10000