allow multiple typeahead

allow multiple typehead by adding
'data-multiple'='true'

-------------example----------
echo $this->Form->autocomplete('recipient', array(
'type' => 'text',
'label' => __d('croogo', 'Email Recipient'),
'class' => 'span10',
'autocomplete' => array(
'default' => $username,
'data-displayField' => 'name',
'data-primaryKey' => 'email',
'data-queryField' => 'name',
'data-multiple' => 'true',
'data-relatedElement' => '#CformRecipient',
'data-url' => $UserEmailApiUrl,
),
));