FIX: re-revert db4f5f99 with updated tests (#88)

The tests were using an incorrect value for the site setting (the name of the group instead of the id).

`no_ads_for_groups` shows groups names in the UI byt actually stores IDs.

test/javascripts/acceptance/adsense-test.js.es6

@@ -4,7 +4,7 @@ import groupFixtures from "fixtures/group-fixtures";
 acceptance("AdSense", {
   loggedIn: true,
   settings: {
-    no_ads_for_groups: "discourse",
+    no_ads_for_groups: "47",
     no_ads_for_categories: "1",
     adsense_publisher_code: "MYADSENSEID",
     adsense_through_trust_level: 2,

test/javascripts/acceptance/dfp-test.js.es6

@@ -4,7 +4,7 @@ import groupFixtures from "fixtures/group-fixtures";
 acceptance("DFP Ads", {
   loggedIn: true,
   settings: {
-    no_ads_for_groups: "discourse",
+    no_ads_for_groups: "47",
     no_ads_for_categories: "1",
     dfp_publisher_id: "MYdfpID",
     dfp_through_trust_level: 2,