re-add lost group_delete js event

JohnDoh

2013-12-29 1fdb55a99eea99eea325c642b4c06d866d0d1b19

 program/js/app.js

@@ -5048,6 +5048,7 @@
  {
    var key = 'G'+prop.source+prop.id;
    if (this.treelist.remove(key)) {
      this.triggerEvent('group_delete', { source:prop.source, id:prop.id });
      delete this.env.contactfolders[key];
      delete this.env.contactgroups[key];
    }