Modified the Wordpress AJAX posts to both Statler and Cake to use the proper Multistep::$global_var

Modified the $api_data_attributes variable in form-multistep.php to be
an array instead of a string for simplicity.  Added 'ptid' as another
parameter that can be collected and passed into the system in
multistep.js.  Fixed an issue where the 'Please wait while we retrieve
school data.' was being displayed multiple times.