Add and apply rubocop rules for empty lines

We were very inconsistent regarding these rules.

Personally I prefer no empty lines around blocks, clases, etc... as
recommended by the Ruby style guide [1], and they're the default values
in rubocop, so those are the settings I'm applying.

The exception is the `private` access modifier, since we were leaving
empty lines around it most of the time. That's the default rubocop rule
as well. Personally I don't have a strong preference about this one.


[1] https://rubystyle.guide/#empty-lines-around-bodies

spec/features/admin/poll/questions/answers/answers_spec.rb

@@ -1,7 +1,6 @@
 require "rails_helper"
 
 describe "Answers" do
-
   before do
     admin = create(:administrator)
     login_as admin.user
@@ -59,5 +58,4 @@ describe "Answers" do
 
     expect("Another title").to appear_before("New title")
   end
-
 end

spec/features/admin/poll/questions/answers/documents/documents_spec.rb

@@ -1,7 +1,6 @@
 require "rails_helper"
 
 describe "Documents" do
-
   before do
     admin = create(:administrator)
     login_as(admin.user)
@@ -38,5 +37,4 @@ describe "Documents" do
 
     expect(page).not_to have_content(document.title)
   end
-
 end

spec/features/admin/poll/questions/answers/images/images_spec.rb

@@ -1,7 +1,6 @@
 require "rails_helper"
 
 describe "Images" do
-
   before do
     admin = create(:administrator)
     login_as(admin.user)
@@ -58,5 +57,4 @@ describe "Images" do
     expect(page).not_to have_css("img[title='#{image.title}']")
     expect(page).not_to have_content(image.title)
   end
-
 end

spec/features/admin/poll/questions/answers/videos/videos_spec.rb

@@ -1,7 +1,6 @@
 require "rails_helper"
 
 describe "Videos" do
-
   before do
     admin = create(:administrator)
     login_as(admin.user)
@@ -29,5 +28,4 @@ describe "Videos" do
     expect(page).to have_content(video_title)
     expect(page).to have_content(video_url)
   end
-
 end