fix modal height for delete wiki page in new ui

Fixes: CNVS-26680

test plan:
- as an admin using new ui
- navigate to a course and click "pages"
- select the cog to allow you to select the trash icon to delete
  the page
- the modal text should no longer be cut off

  examples:
  old bad exp: http://screencast.com/t/M9pIDCFxkPna
  new good exp: http://screencast.com/t/gNauRojonc

- ensure experience is good/consistent using old ui

Change-Id: I30645ab4ce28d36f65b781991b9a72ec15cf60b0
Reviewed-on: https://gerrit.instructure.com/71389
Tested-by: Jenkins
Reviewed-by: Colleen Palmer <colleen@instructure.com>
Product-Review: Colleen Palmer <colleen@instructure.com>
QA-Review: Myller de Araujo <myller@instructure.com>

app/coffeescripts/views/wiki/WikiPageDeleteDialog.coffee

@@ -10,7 +10,7 @@ define [
     fixDialogButtons: false
     title: I18n.t 'delete_dialog_title', 'Delete Wiki Page'
     width: 400
-    height: 160
+    height: 'auto'
 
   class WikiPageDeleteDialog extends DialogFormView
     setViewProperties: false