FIX: Groups post page was broken.

Also added integration tests so we don't miss this breaking in the
future.

test/javascripts/integration/groups-test.js.es6

@@ -0,0 +1,12 @@
+integration("Groups");
+
+test("Browsing Groups", function() {
+  visit("/groups/discourse");
+  andThen(function() {
+    ok(count('.user-stream .item') > 0, "it has stream items");
+  });
+  visit("/groups/discourse/members");
+  andThen(function() {
+    ok(count('.group-members tr') > 0, "it lists group members");
+  });
+});