Merge branch 'rubocop/EmptyLinesAroundModuleBody' into 'master'

Enable Style/EmptyLinesAround Module/Class Body cop

## What does this MR do?
Enable a new rubocop cops as discussed here: https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/1877/diffs#note_13021078

## Are there points in the code the reviewer needs to double check?
May be a good idea to send a message to people to prevent `master` red because of the new cop.

## Why was this MR needed?
We want to improve code style and not waste endbosses time checking style manually

## What are the relevant issue numbers?

## Screenshots (if relevant)

## Does this MR meet the acceptance criteria?

- [ ] [CHANGELOG](https://gitlab.com/gitlab-org/gitlab-ce/blob/master/CHANGELOG) entry added
- [ ] [Documentation created/updated](https://gitlab.com/gitlab-org/gitlab-ce/blob/master/doc/development/doc_styleguide.md)
- [ ] API support added
- Tests
  - [ ] Added for this feature/bug
  - [ ] All builds are passing
- [ ] Conform by the [style guides](https://gitlab.com/gitlab-org/gitlab-ce/blob/master/CONTRIBUTING.md#style-guides)
- [ ] Branch has no merge conflicts with `master` (if you do - rebase it please)
- [ ] [Squashed related commits together](https://git-scm.com/book/en/Git-Tools-Rewriting-History#Squashing-Commits)

See merge request !5692

.rubocop.yml

@@ -153,11 +153,11 @@ Style/EmptyLinesAroundBlockBody:
 
 # Keeps track of empty lines around class bodies.
 Style/EmptyLinesAroundClassBody:
-  Enabled: false
+  Enabled: true
 
 # Keeps track of empty lines around module bodies.
 Style/EmptyLinesAroundModuleBody:
-  Enabled: false
+  Enabled: true
 
 # Keeps track of empty lines around method bodies.
 Style/EmptyLinesAroundMethodBody:

app/helpers/avatars_helper.rb

 module AvatarsHelper
-
   def author_avatar(commit_or_event, options = {})
     user_avatar(options.merge({
       user: commit_or_event.author,
@@ -26,5 +25,4 @@ module AvatarsHelper
       mail_to(options[:user_email], avatar)
     end
   end
-
 end

lib/banzai/filter/video_link_filter.rb

 module Banzai
   module Filter
-
     # Find every image that isn't already wrapped in an `a` tag, and that has
     # a `src` attribute ending with a video extension, add a new video node and
     # a "Download" link in the case the video cannot be played.
     class VideoLinkFilter < HTML::Pipeline::Filter
-
       def call
         doc.xpath(query).each do |el|
           el.replace(video_node(doc, el))
@@ -54,6 +52,5 @@ module Banzai
         container
       end
     end
-
   end
 end

lib/gitlab/import_export/avatar_restorer.rb

 module Gitlab
   module ImportExport
     class AvatarRestorer
-
       def initialize(project:, shared:)
         @project = project
         @shared = shared