CBQE:0 use.log extension if enclosing filename within quotes else grep doesn't return correct results:

Change-Id: I356b2e457d360057ee27cdcb19d7020523d70c4a
Reviewed-on: http://review.couchbase.org/41062
Tested-by: buildbot <build@couchbase.com>
Reviewed-by: Sangharsh Agarwal <sangharsh.agarwal@globallogic.com>
Tested-by: Sangharsh Agarwal <sangharsh.agarwal@globallogic.com>