Mongo filter support

[rclai]

This is in regards to #148.

[aslagle]

I'm about to merge a branch with server-side filtering, and I had to have a separate mongo selector argument on the server side, so I guess this would make the client options more consistent. (Otherwise, you can just pass in collection.find(filter) as the collection.)

There'd be some merge conflicts - I moved the filter code and I've been calling the separate argument selector.

[frabrunelle]

👍 for having a mongo selector argument on the client side. currently I am getting some warnings with astronomy when I specify collection.find(filter) instead of collection. It's not causing any bugs but I don't like having warnings in my console.

Trying to set a value of the "_modifiers" field that does not exist in the "Member" class
Trying to set a value of the "_original" field that does not exist in the "Member" class
Trying to set a value of the "_errors" field that does not exist in the "Member" class
Trying to set a value of the "_isNew" field that does not exist in the "Member" class

So I'm thinking that by having a separate argument for specifying the mongo selector, it will fix my issue, which I believe is due to this part of the code.

The other solution would be to add this code there:

// copy over fields from astronomy package
collection._modifiers = cursor._modifiers;
collection._original = cursor.collection._original;
collection._errors = cursor.collection._errors;
collection._isNew = cursor.collection._isNew;

Let me know which solution you prefer. Cheers.