Unescape URL param values in ComponentMeta

#### Problem

When using an array in the URL parameters (batch request), they would be handed back in the JSON response as a URL encoded string instead of a hash.

#### Solution

Unescape all URL parameter values in [ComponentMeta](https://github.com/BBC-News/alephant-broker/blob/master/lib/alephant/broker/component_meta.rb#L18).

Example response:

```json
{
    "batch_id": "test",
    "components": [
        {
            "component": "test",
            "options": {
                "routing": "{\"superhero\"=>\"batman\", \"city\"=>\"gotham\"}",
                "region": "global"
            },
            "status": 200,
            "content_type": "text/html",
            "body": "<h1>I'm batman!</h1>"
        }
    ]
}
```

![avengers_hammer](https://cloud.githubusercontent.com/assets/2796074/4881847/400f8dd6-634e-11e4-939e-369604a96287.gif)