measured_quantity attributes

the measured_quantity container should not have the value unit and type in the attributes, they should instead be in the values attributes. Right now they are in both (so redundant)

Instead of:

"measured_quantity": {
        "attributes": {
            "source": [
                "<source>"
            ],
            "unit": "<unit>",
            "value_type": "<average/approximate/range>",
            "description": "<text>"
        },
        "content": {
            "value": {
                "attributes": {
                    "source": [
                        "<source>"
                    ],
                    "description": "<text>",
                    "unit": "<unit>",
                    "value_type": "<average/approximate/range>"
                },
                "body": [
                    999
                ]
            },
            "uncertainty": {
                "attributes": {
                    "source": [
                        "<source>"
                    ],
                    "description": "<text>",
                    "unit": "<unit>",
                    "unc_type": "<relative/absolute/resolution>"
                },
                "body": [
                    999
                ]
            }
        }
    }

it should be:

"measured_quantity": {
        "attributes": {
            "source": [
                "<source>"
            ],
            "description": "<text>"
        },
        "content": {
            "value": {
                "attributes": {
                    "source": [
                        "<source>"
                    ],
                    "description": "<text>",
                    "unit": "<unit>",
                    "value_type": "<average/approximate/range>"
                },
                "body": [
                    999
                ]
            },
            "uncertainty": {
                "attributes": {
                    "source": [
                        "<source>"
                    ],
                    "description": "<text>",
                    "unit": "<unit>",
                    "unc_type": "<relative/absolute/resolution>"
                },
                "body": [
                    999
                ]
            }
        }
    }