Added Javadoc for all the lazy BSON object types.

  JAVA-1428
Removed LazyWriteableDBObject and related classes.  These classes are poorly designed and violate the implicit contract of LazyBSONObject, which
allows the contents of the object to be piped to an output stream.  Doing so with a LazyWriteableDBObject instance will ignore any modifications
made to that instance.

  JAVA-1537