calendar

Merge pull request #29 in FREEPBX/calendar from ~NTHUMANN/calendar:bugfix/FREEPBX-20217-unable-to-set-calendar-repeat-by-option-to-date-of-the-month-year_14 to release/14.0

* commit 'ff17661eae520d5875ca23fa994c425e8b2f9cf1':
  Fixes FREEPBX-20217: check for byday length instead of existence (v14.0)