if licenses array only contains one license remove the array

e.g. jquery-ui would return:
```
    "jquery-ui@1.11.1": {
        "licenses": [
            "MIT"
        ],
        "repository": "https://github.com/jquery/jquery-ui"
    },
```
i changed this to:
```
    "jquery-ui@1.11.1": {
        "licenses": "MIT",
        "repository": "https://github.com/jquery/jquery-ui"
    },
```