#91 Adding permission exempt_expiration results in python x not in list error

[bill halpin]

There are errors in Admin.js that prevent adding exempt_expiration permissions to users. All the checkboxes in this module are named "checkbox_" + id.

This creates problems as more than one checkbox_id is possible on the same page and the elements are selected thusly: $("#checkbox_"+id) so the first element is always retrieved. The first element in this context is the element named 'select_row" not the element named 'select_permission' so the wrong element is checked and the action fails.

To fix the problem I changed the permissions elements to p_checkbox_id.