Normalize page paths

Normalize page paths so they can be accessed by `page_path(:id)`.

The benefit of this is that we can add any arbitrary amount of pages
without affecting the routing layer.

app/controllers/pages_controller.rb

@@ -1,52 +1,7 @@
 class PagesController < ApplicationController
   skip_authorization_check
 
-  def accessibility
-  end
-
-  def census_terms
-  end
-
-  def conditions
-  end
-
-  def general_terms
-  end
-
-  def privacy
-  end
-
-  def coming_soon
-  end
-
-  def how_it_works
-  end
-
-  def how_to_use
-  end
-
-  def more_information
-  end
-
-  def opendata
-  end
-
-  def participation
-  end
-
-  def proposals_info
-  end
-
-  def participation_facts
-  end
-
-  def participation_world
-  end
-
-  def verify
-  end
-
-  def blog
-    redirect_to "http://diario.madrid.es/participa/"
+  def show
+    render action: params[:id]
   end
 end