CBQE-0:fix grammatical error in log

Change-Id: Ia8b8e62a9a275c992e2f26cf530e32c24ca15c18
Reviewed-on: http://review.couchbase.org/37450
Reviewed-by: Iryna Mironava <irynamironava@yandex.ru>
Tested-by: Iryna Mironava <irynamironava@yandex.ru>