Revert "if we pass in actual agent objects to the dimension manager's constructor, they won't have a reference to the dimension manager in time, so pass in config instead. Also if model is passed in as a config object, transform it into a real model, see https://github.com/opengeo/mapstory/issues/535 for details"

This reverts commit e7281966bd7334bfe70c798b41f6adde0562119f.