Change score name to array in meta json

Change score name to array in meta json

outputmetadata score name was single string, but needs to change to
handle yolo models.(multiple names)
`before`
"score" :
    {
        "name" : "some name",
        ...
    }
`after`
"score" :
    {
        "name" : ["some name"],
        ...
    }

Change-Id: Ie76b38ad6eb7665300b556c2d9ce0be576a537f3
Signed-off-by: Kwanghoon Son <k.son@samsung.com>