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
I'm not sure I understand what's going on here - could you add a comment to say why you're converting to a JSON string and then back again?