Problem

`pymongo.collection.Collection.count_documents()` does not accept `min` and `max`, even though these kwargs can be passed to `pymongo.collection.Collection.find()` and can alter the document count. This makes `count_documents()` useless for certain queries.

Definition of half-way done

`pymongo.collection.Collection.count_documents()` accepts kwargs `min` and `max` and returns the correct number of documents.

Definition of fully done

`pymongo.collection.Collection.count_documents()` accepts all kwargs of `pymongo.collection.Collection.find()` and returns the correct document count when users write:
```
find_kwargs = {...}
with pymongo.MongoClient(host, port) as mongo:
    coll = mongo[database][collection]
    n_docs = coll.count_documents(**find_kwargs)
    with coll.find(**find_kwargs) as cursor:
        # do stuff    
```

Idea for alternative, best solution

`pymongo.collection.Collection.find()` itself should give access to the total number of matched documents. This improvement would make `pymongo.collection.Collection.count_documents()` redundant.