Remove useless answers show view

Until now, in order to edit an answer, we had to click on its title on
the table and then on the "Edit answer" link.

That was tedious and different from what we usually do in the admin
section. Furthermore, the code for the answers table was written twice
and when we modified it we forgot to update the one in the `show`
action, meaning the table here provided less information than the
information present in the answers tables.

Co-Authored-By: Javi Martín <javim@elretirao.net>

config/routes/admin.rb

@@ -169,7 +169,7 @@ namespace :admin do
     end
 
     resources :questions, shallow: true do
-      resources :answers, except: [:index, :destroy], controller: "questions/answers", shallow: false
+      resources :answers, except: [:index, :show, :destroy], controller: "questions/answers", shallow: false
       resources :answers, only: [], controller: "questions/answers" do
         resources :images, controller: "questions/answers/images"
         resources :videos, controller: "questions/answers/videos"
@@ -323,6 +323,10 @@ resolve "Poll::Officer" do |officer, options|
   [:officer, options.merge(id: officer)]
 end
 
+resolve "Poll::Question::Answer" do |answer, options|
+  [:question, :answer, options.merge(question_id: answer.question, id: answer)]
+end
+
 resolve "Poll::Question::Answer::Video" do |video, options|
   [:video, options.merge(id: video)]
 end