Allow init Query<Model> object

[andrefmsilva]

From source code looks like Query init method is private and i want to create it myself and reuse queries in multiple places.
For example, we can abstract repository that fetch realm object using an ObjectQuery enum, where each case generate a different Query and Sort descriptions.

I have this abstraction but with current implementation i need to use NSPredicate and loose Query features.

It's a nice to have something like a Query builder that returns a Query object and we can use it or just convert it to predicate.