Fix error when a shim has a non-steal dep and a exports function

If a shim specifies a non-steal dependency (via deps) and an exports function, Steal will throw a JS error because the module.options is a String just before makeOptions is called.

This fix catches this case and turns options into an Object with the id set to the String value as expected.

__stealconfig.js__
```js
...
shim: {
    'dollar': {
        exports: 'dollar'
    },
    'dollar.plugin': {
        deps: ['dollar'],
        exports: function($) {
            ...
        }
    }
}
...