SERVER-11611: dbcommand ported to new collection interface

Signed-off-by: Matt Kangas <matt.kangas@mongodb.com>
SERVER-11611: convert mapreduce to new collection encapsulation

Signed-off-by: Matt Kangas <matt.kangas@mongodb.com>
SERVER-11611 port rename_collection over to new collection interface

Signed-off-by: Matt Kangas <matt.kangas@mongodb.com>