tidied hook.js

Change-Id: Ie1fb7877ddb3aecab76711a0c7ec69ecd2847de1
Reviewed-on: http://review.couchbase.org/28596
Reviewed-by: Aliaksey Kandratsenka <alkondratenko@gmail.com>
Tested-by: Aliaksey Kandratsenka <alkondratenko@gmail.com>