Extract legacy parts of the codebase into its own module

app/views/shared/_histogram.html.haml

@@ -1,12 +0,0 @@
-- histogram = data.responses.map(&:answer_index_with_reverse).group_by { |a| a.to_s }
-%table.answers
-  %tbody
-    - data.question.options_with_reverse.each_with_index do |option, index|
-      %tr.answer
-        - group = histogram[(index + 1).to_s]
-        - width = (100 * (group.blank? ? 0 : group.length)) / histogram.values.flatten.length
-        %td.text
-          = "#{option}:"
-          = group.blank? ? 0 : group.length
-        %td.count
-          %div{class: "bar#{index}", style: "width: #{width}%"}