- Make sure Query#fields returns a hash, not an array.
- Fix query limit by passing limit number to cursor and having it enforce the
limit. (Database returns limit as first batch, but will continue to return
data after the limit if requested.)
Improvements:
- Query#new can take a single field name instead of an array
- A few doc comment improvements here and there.
- Introduced OrderedHash because db commands require that the command key be
first.
- Fixed BSON (de)serialization of object ids.
- Simplified @coll.drop_indexes.
- Renamed some method parameters to make their type more clear (for example,
"collection" became "collection_name").
- Got the index_information test working.
