added code to remove replacement text if attribute is not set.
This MR is to add code that will remove the token's replacement text if the corresponding CAS attribute is not set.
A good way to test this is to set up CAS attribute tokens on any page that can be reached anonymously, and then browse to that page anonymously. Before this work is applied, you would see the text [cas:attribute:ATTRIBUTE-NAME]
. After this work is applied, no text will be printed in this scenario.
For clarity -- anonymous in this case means no Drupal session, and no CAS session.