Commercial fluid 250 template

This ties up with the template in DFP, (code below) and pulls in the images and options from DFP to generate the fluid 250 style advert.

Guidelines for use of the template is here;
https://docs.google.com/a/guardian.co.uk/document/d/1n7Si4ZmJu9rQ5OxgXm7nCwVO6LbnrkabNi5ErpytC4k/edit?usp=sharing

DFP code;
```
<script type="application/json" class="breakout__script">
{
    "name": "fluid250",
    "params": {
        "link": "%%CLICK_URL_ESC%%[%Link%]",
        "trackingPixel": "[%Trackingpixel%]",
        "backgroundColor": "[%Backgroundcolour%]",
        "backgroundImage": "[%BackgroundImage%]",
        "backgroundRepeat": "[%Backgroundrepeat%]",
        "backgroundPosition": "[%Backgroundposition%]",
        "layerOneBGImage": "[%Layer1backgroundimage%]",
        "layerOneBGPosition": "[%Layer1backgroundimageposition%]",
        "layerTwoBGImage": "[%Layer2backgroundimage%]",
        "layerTwoBGPosition": "[%Layer2backgroundimageposition%]",
        "layerThreeBGImage": "[%Layer3backgroundimage%]",
        "layerThreeBGPosition": "[%Layer3backgroundimageposition%]",
        "layerOneBGImageM": "[%Layer1backgroundimagemobile%]",
        "layerOneBGPositionM": "[%Layer1backgroundimagepositionmobile%]",
        "layerTwoBGImageM": "[%Layer2backgroundimagemobile%]",
        "layerTwoBGPositionM": "[%Layer2backgroundimagepositionmobile%]",
        "layerThreeBGImageM": "[%Layer3backgroundimagemobile%]",
        "layerThreeBGPositionM": "[%Layer3backgroundimagepositionmobile%]"
    }
}
</script>
```
why `top-banner`? can't this template be used anywhere?