Allow string parameters to be considered as id to build a view query url using first().

When a page is loaded and the url parsed for the first time, we don't have any reference of the resource url (i.e the $links data).

Using:
```js
model('Resources').first({ id: 'myid' })
```

To get the data back, will generate a //api/resources?id=myid url

However index calls is also used to get a lot of datas and this become problematic when we want to embed all the stuff inside an index call.

this PR allow the following syntax

```js
model('Resources').first('myid')
```

which will generate a //api/resources/myid url

This way we differenciate what should be returned by an index call (i.e. the minmum) and what is returned by a view call (the whole document with embeded datas)