$elemMatch not matching

Hi Eugene,

Thanks for the module!

I have a query regarding `$elemMatch` condition. I have an input JSON object represented something like:

```
{
users : [
{
name : 'john doe'
}
]
}
```

My JSON query looks like:

```
{
users : {
$elemMatch : {
name : 'john doe'
}
}
}
```

However, this isn't matching the input object at present, even though is a valid matching MongoDB query. Any ideas?

Thanks.