style(Account Profile Tray) Allow initials in avatar
style(Account Profile Tray) Allow initials in avatar

Fixes: UIDEV-224

test plan:
- click account from main nav - ensure image is present if the
  user has uploaded an image for their avatar
- log in as a user that does NOT have an image uploaded to ensure
  the users initials show in the tray avatar
  example: https://cl.ly/e16aef986a11

Change-Id: Ie5e11290c4cccd9eb322afff1447c700500dad2e
Reviewed-on: https://gerrit.instructure.com/163938
Tested-by: Jenkins
Reviewed-by: Jeremy Stanley <b3f594e10a9edcf5413cf1190121d45078c62290@instructure.com>
QA-Review: Dan Sasaki <ae19fabf7fe19dff310008c9b6a4d2ec84d311d8@instructure.com>
Reviewed-by: Ryan Shaw <ea3cd978650417470535f3a4725b6b5042a6ab59@instructure.com>
Product-Review: Mary Jane Anderson <bfb9d3817d27ddfdcd2a6c0c878e2771b3b2c4a7@instructure.com>

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