Bump version 1.2.3

Change-Id: Iee215b9ca70dca7db1e1d6c08c5a3ceed6ab29e4
Reviewed-on: http://review.couchbase.org/25446
Tested-by: Sergey Avseyev <sergey.avseyev@gmail.com>
Reviewed-by: John C. Zablocki <john@couchbase.com>