Write task to migrate budget admins and valuators

If we didn't run this task, investments for existing budgets wouldn't
show their administrator/valuators as an option when we're editing them,
leading to data loss.

lib/tasks/consul.rake

@@ -5,6 +5,7 @@ namespace :consul do
   desc "Runs tasks needed to upgrade from 1.0.0 to 1.1.0"
   task "execute_release_1.1.0_tasks": [
     "budgets:set_original_heading_id",
-    "migrations:valuation_taggings"
+    "migrations:valuation_taggings",
+    "migrations:budget_admins_and_valuators"
   ]
 end