Routine rubocop fixes (#4924)

Ran rubocop -a and rubocop --auto-gen-config

.rubocop_todo.yml

@@ -1,12 +1,12 @@
 # This configuration was generated by
 # `rubocop --auto-gen-config`
-# on 2019-11-19 11:07:38 +0100 using RuboCop version 0.76.0.
+# on 2019-11-25 17:24:08 +0100 using RuboCop version 0.76.0.
 # The point is for the user to remove these configuration records
 # one by one as the offenses are removed from the code base.
 # Note that changes in the inspected code, or installation of new
 # versions of RuboCop, may require this file to be generated again.
 
-# Offense count: 232
+# Offense count: 230
 Metrics/AbcSize:
   Max: 75
 
@@ -31,11 +31,16 @@ RSpec/ExampleLength:
     - 'spec/requests/api/v0/articles_spec.rb'
     - 'spec/requests/display_ad_events_spec.rb'
 
-# Offense count: 452
+# Offense count: 455
 # Configuration parameters: AggregateFailuresByDefault.
 RSpec/MultipleExpectations:
   Max: 8
 
+# Offense count: 1
+RSpec/SubjectStub:
+  Exclude:
+    - 'spec/models/article_spec.rb'
+
 # Offense count: 1
 # Configuration parameters: Include.
 # Include: app/helpers/**/*.rb
@@ -56,7 +61,7 @@ Rails/OutputSafety:
     - 'app/models/message.rb'
     - 'app/views/articles/feed.rss.builder'
 
-# Offense count: 24
+# Offense count: 25
 # Cop supports --auto-correct.
 # Configuration parameters: AutoCorrect, EnforcedStyle.
 # SupportedStyles: nested, compact
@@ -69,7 +74,7 @@ Style/GuardClause:
   Exclude:
     - 'app/models/article.rb'
 
-# Offense count: 3185
+# Offense count: 3216
 # Cop supports --auto-correct.
 # Configuration parameters: AutoCorrect, AllowHeredoc, AllowURI, URISchemes, IgnoreCopDirectives, IgnoredPatterns.
 # URISchemes: http, https

spec/factories/activesupport_events.rb

@@ -1,5 +1,5 @@
 FactoryBot.define do
-  factory :activesupport_event, class: ActiveSupport::Notifications::Event do
+  factory :activesupport_event, class: "ActiveSupport::Notifications::Event" do
     name { "audit.log" }
     time { Timecop.freeze(Time.zone.now) }
     ending { time + 10.seconds }

spec/factories/webhook_endpoints.rb

@@ -1,5 +1,5 @@
 FactoryBot.define do
-  factory :webhook_endpoint, class: Webhook::Endpoint do
+  factory :webhook_endpoint, class: "Webhook::Endpoint" do
     target_url { Faker::Internet.url(scheme: "https") }
     events { Webhook::Event::EVENT_TYPES }
     user