Added plural ordered to-many KVO support; removed incorrect add<Key>Object: behavior
Added plural ordered to-many KVO support; removed incorrect add<Key>Object: behavior

berkus/cocotron,liruqi/cocotron,liruqi/cocotron,liruqi/cocotron,berkus/cocotron,berkus/cocotron,berkus/cocotron,liruqi/cocotron