Order translations using ruby

Joining the translations table caused duplicate records to appear.
Ordering with SQL is simply too hard because we need to consider
fallback locales.

Thanks Senén for providing most of the tests in the poll spec.

app/controllers/polls_controller.rb

@@ -12,8 +12,9 @@ class PollsController < ApplicationController
   ::Poll::Answer # trigger autoload
 
   def index
-    @polls = @polls.not_budget.public_polls.send(@current_filter).includes(:geozones)
-                              .sort_for_list.page(params[:page])
+    @polls = Kaminari.paginate_array(
+      @polls.public_polls.not_budget.send(@current_filter).includes(:geozones).sort_for_list
+    ).page(params[:page])
   end
 
   def show

app/controllers/valuation/budget_investments_controller.rb

@@ -75,9 +75,7 @@ class Valuation::BudgetInvestmentsController < Valuation::BaseController
     def heading_filters
       investments = @budget.investments.by_valuator(current_user.valuator.try(:id))
                                        .visible_to_valuators.distinct
-      investment_headings = Budget::Heading.joins(:translations)
-                                           .where(id: investments.pluck(:heading_id).uniq)
-                                           .order(name: :asc)
+      investment_headings = Budget::Heading.where(id: investments.pluck(:heading_id)).sort_by(&:name)
 
       all_headings_filter = [
                               {