NBC is proudly entering “The Gilded Age.” For those missing the Dowager Countess’ condescending glares or the evening ring of the dinner bell, there’s a new Julian Fellowes drama on tap at NBC that brings an upstairs/downstairs tale Stateside. The Gilded Age in 1880s New York City was a period of immense social upheaval, of huge fortunes made and lost, and of palaces that spanned the length of Fifth Avenue.