call as_json on hashes and arrays before stringifying
call as_json on hashes and arrays before stringifying

will cast any nested objects

fixes #PLAT-4236

Change-Id: I36670cc6dbd5213053036685d6c3cd7f5fa0853e
Reviewed-on: https://gerrit.instructure.com/185188
Reviewed-by: Cody Cutrer <c4fe2b1d90ef8f2548c8aeabfa633434316f0305@instructure.com>
QA-Review: Cody Cutrer <c4fe2b1d90ef8f2548c8aeabfa633434316f0305@instructure.com>
Product-Review: Cody Cutrer <c4fe2b1d90ef8f2548c8aeabfa633434316f0305@instructure.com>
Tested-by: Jenkins

djbender/canvas-lms,djbender/canvas-lms,sfu/canvas-lms,sfu/canvas-lms,sfu/canvas-lms,djbender/canvas-lms,sfu/canvas-lms,sfu/canvas-lms,sfu/canvas-lms,sfu/canvas-lms,djbender/canvas-lms