ScheduledReminder, Extensions, Cxn - Fix copy-pasted header

ScheduledReminder, Extensions, Cxn - Fix copy-pasted header

These are files which I've been personally involved with for which the
header information is inaccurate. I believe the headers were copy-pasted
blindly from another file.

Notes on how I would know:

 * Scheduled reminders were originally written by CiviCRM LLC and WebAccess
   under contract with Benton Consulting (where I was point-of-contact).
 * I was the original author of CiviConnect and Extension BAO/API.
 * In both cases, we had an agreement that CiviCRM would own that work.