Updating API for consistency.

Using the jQuery API as a guide.  Current `then` functions like `done`

This is still incomplete, but the current implementation is more in line with the target
MongoDB consistency update

Updating collection insert and find to match MongoDB options (closer).

Also adding Cursor class for handling methods that create cursor objects and wrap them with deferreds
Breaking out Collection/Cursor implementation

These are now separate files, so it should be easier to implement the MongoDB API intent