Make datetime tests fake unit tests.

tests/feeds_date_time.test

@@ -12,7 +12,7 @@
  * Not inheriting from Feeds base class as ParserCSV should be moved out of
  * Feeds at some time.
  */
-class FeedsDateTimeTest extends FeedsUnitTestHelper {
+class FeedsDateTimeTest extends FeedsWebTestCase {
   protected $profile = 'testing';
 
   public static function getInfo() {