Add 'nin' and 'in' to query.

This methods are used with field name and array.

db.query().nin('fieldname',['a', 'b']);
db.query().in('fieldname',['a', 'b']);

Read below for more information.
http://docs.mongodb.org/manual/reference/operator/query/in/
http://docs.mongodb.org/manual/reference/operator/query/nin/
Fix bugs in collection.find().

QueryOpts is immutable, skip() and batchSize() doesn't change itself, it
creates new one.

Both skipN and batchSieN has default value 0.