value.Bytes() changed to value.MarshalJSON().

Change-Id: I32b972579ee153d4851aacd1488f5223cb410184
Reviewed-on: http://review.couchbase.org/42558
Reviewed-by: Chris Hillery <ceej@couchbase.com>
Reviewed-by: Pratap Chakravarthy <prataprc@couchbase.com>
Tested-by: Pratap Chakravarthy <prataprc@couchbase.com>