Premitium's post in Add "Save and Stay" button to helper form. was marked as the answer
This is what I found as a solutions:
'buttons' => array( 'save-and-stay' => array( 'title' => $this->l('Save and Stay'), 'name' => 'submitAdd'.$this->table.'AndStay', 'type' => 'submit', 'class' => 'btn btn-default pull-right', 'icon' => 'process-icon-save', ), ),
Premitium's post in Module is downloaded successfully but doesn't show in list for insall was marked as the answer
He had the name of the folder /mymodcarriermaster/ and the php file inside the folder is mymodcarrier.php I removed the master part from the folder and it is all there now.