SERVER-11178: more IndexCatalog work
SERVER-11178: IndexLegacy partly to IndexCatalog
SERVER-11178: IndexLegacy::getMissingField using IndexCatalog
SERVER-11178: IndexScan now uses IndexCatalog classes
SERVER-11178: index building now all with IndexCatalog, CatalogHack out of all new paths
SERVER-11433: group a non-existant collection should not be an error