changes officer assignments to polls via new model/relation

app/models/poll/officer_assignment.rb

@@ -0,0 +1,8 @@
+class Poll
+  class OfficerAssignment < ActiveRecord::Base
+    belongs_to :officer
+    belongs_to :booth_assignment
+
+    delegate :poll_id, :booth_id, to: :booth_assignment
+  end
+end