show card on preview panel.

refactor user and group cards

refactor userLoading to loading

add logic to display cards above mentions for fixed placements

test/javascripts/acceptance/user-card-test.js.es6

@@ -11,4 +11,17 @@ QUnit.test("card", assert => {
     assert.ok(visible('#user-card'), 'card should appear');
   });
 
-});
+});
+
+
+QUnit.test("group card", assert => {
+  visit('/t/301/1');
+
+  assert.ok(invisible('#group-card'), 'user card is invisible by default');
+  click('a.mention-group:first');
+
+  andThen(() => {
+    assert.ok(visible('#group-card'), 'card should appear');
+  });
+
+});