findAndModify syntactic sugar

Hi,

This method is really missing, instead of constructing BasicDBObject() like this:

	Query query = DBQuery.is("authToken", authToken);
	BasicDBObject update = new BasicDBObject("$set", new BasicDBObject("lastAccess", System.currentTimeMillis()));
	session = coll.sessions().findAndModify(query, null, null, false, update, true, false);

one can use builder for creating an update query:

	Query query = DBQuery.is("authToken", authToken);
	Builder update = DBUpdate.set("lastAccess", System.currentTimeMillis());
	session = coll.sessions().findAndModify(query, null, null, false, update, true, false);