Prevents withdrawn proposals from being marked as ignored.
Prevents withdrawn proposals from being marked as ignored.

Prevents ignore button from being rendered on the org admin's proposal review page if the proposal has been marked as withdrawn by a student. Also returns an HTTP 403 if a User attempts to fake a POST request with valid data to change a withdrawn proposal to 'ignored' without using the review form.

Fixes Issue 1515.

rhyolight/nupic.son,rhyolight/nupic.son,rhyolight/nupic.son