Rename "Upload Image" dialog to "Upload File" to match purpose

Summary: Fixes T3940.

Test Plan: Clicked button, looked at dialog.

Reviewers: epriestley, #blessed_reviewers

Reviewed By: epriestley

CC: nmalcolm, Korvin, epriestley, aran

Maniphest Tasks: T3940

Differential Revision: https://secure.phabricator.com/D7287

src/applications/files/controller/PhabricatorFileUploadDialogController.php

@@ -9,7 +9,7 @@ final class PhabricatorFileUploadDialogController
 
     $dialog = id(new AphrontDialogView())
       ->setUser($user)
-      ->setTitle(pht('Upload Image'))
+      ->setTitle(pht('Upload File'))
       ->appendChild(pht(
         'To add files, drag and drop them into the comment text area.'))
       ->addCancelButton('/', pht('Close'));