fix adding appointment details in public feed without appointment
fix adding appointment details in public feed without appointment

closes #ADMIN-1406

Change-Id: Ide5c558fa520cc92b7e43b28bacd2af07b17978e
Reviewed-on: https://gerrit.instructure.com/163067
Tested-by: Jenkins
Reviewed-by: Steven Burnett <a0b450117c5d20a22d5c4d52bb8ae13adee003d8@instructure.com>
Product-Review: James Williams  <3a5f4ed991dbfa5c9ef76ad729d240ca12f62180@instructure.com>
QA-Review: James Williams  <3a5f4ed991dbfa5c9ef76ad729d240ca12f62180@instructure.com>

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