truncate new conversation message sms
truncate new conversation message sms

fixes COMMS-1924

Test Plan:
- send a message to a user with a sms cc
- go to ther /user/<user-id>/messages
- notice the truncated text matches the format of
  "New Canvas message from [user_name]"

Change-Id: Ief9d481bee3ff35128906abb56429ba7886a5c22
Reviewed-on: https://gerrit.instructure.com/184646
Tested-by: Jenkins
Product-Review: Steven Burnett <a0b450117c5d20a22d5c4d52bb8ae13adee003d8@instructure.com>
Reviewed-by: Ryan Norton <65299b45178f94900ff304765e8fbf07bd13b331@instructure.com>
QA-Review: Ryan Norton <65299b45178f94900ff304765e8fbf07bd13b331@instructure.com>

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