Update to determine sis enrollment sections

Changes for sections:

(1) SIS section id that matches the current course instance id, will appear first on the list

(2) Those sections with a sis section id which is also a course instance id will appear above those sections that either do not have a sis section id or does not have a course instance id
It may be a personal thing, but I find the double negative a little awkward - could
  if slist['sis_section_id'] != None:
be clearer?