[cbc] Fix observe output formatting

Change-Id: I24be98a67929ab6b0c211cb697da933b30c9ee7a
Reviewed-on: http://review.couchbase.org/26575
Reviewed-by: Sergey Avseyev <sergey.avseyev@gmail.com>
Tested-by: Sergey Avseyev <sergey.avseyev@gmail.com>