Add hover color to upload files area.

Summary: Adds the hover color to the upload images area on Create Mock.

Test Plan: Hover image, get background change.

Reviewers: epriestley, btrahan

Reviewed By: epriestley

CC: aran, Korvin, AnhNhan

Differential Revision: https://secure.phabricator.com/D5291

src/applications/pholio/controller/PholioMockEditController.php

@@ -183,6 +183,7 @@ final class PholioMockEditController extends PholioController {
             ->setValue($files)
             ->setName('file_phids')
             ->setLabel(pht('Images'))
+            ->setActivatedClass('aphront-textarea-drag-and-drop')
             ->setError($e_images);
     }