Fixed documentation of return value for  BSONObject.put to indicate that it returns the previous value associated with the given key.
Also fixed some Javadoc in BSONObject implementations.

  JAVA-1502
Added missing @Override annotations
Added a way to disable batch size tracking on DBCursor in order to avoid the list which tracks each batch size from growing
indefinitely (a problem mostly for high-volume tailable cursors).

  JAVA-591