Hi,
One of my friend, CEC Inland Jan2018 applicant just mentioned CELPIP number as requested in the application form, however upon his submission CIC sent an mail to upload CELPIP scan copy.
Though we don't have separate field to upload IELTS/CELPIP scan copy, most of the applicant(almost everyone from my Organisation) uploaded IELTS/CELPIP score sheet under Education section.
Now, no harm if you are uploading IELTS score in education section or if you are not loading CIC will send mail to upload.