Add filtered collection creator

Add a method that builds a copy of the of the entity store with only filtered model.
Add a spec to verify.
Add models back to filtered collection when within

When a model is added to the entity store and it is within the limits of the filter
also add it to the filtered collection.
Convert object literals into models when passed in

When object literals are passsed in to the add method, convert them
to the appropriate model type first.
Remove models in entity store by filtered

Filtered collection should be able to remove models the from original entity store
when it has its models removed.
Entity store remove removes models from filtered

Add event handler to remove models from filtered collection when models are removed from the
entity store.