fixes CNVS-1171
test plan:
* full conversations regression test
* initiate a conversation with a user from another shard
* reply to that conversation from both the sender and the
receiver
* repeat for a group conversation involving two or more
shards
* repeat for huge batch conversations with hundreds of
users and two or more shards
* known NOT working yet:
* re-using the correct cross-shard private conversation
* probably the tagging of messages with Course x,
Group y, etc.
Change-Id: I52549039875941cd518077cea4e28bfd2bc10dbf
Reviewed-on: https://gerrit.instructure.com/16523
Reviewed-by: Cody Cutrer <cody@instructure.com>
QA-Review: Clare Hetherington <clare@instructure.com>
Tested-by: Jenkins <jenkins@instructure.com>
Cody Cutrer