Rick Lewis, whose Nashville fried chicken spot Southern proved a smash hit in Midtown, is going out on his own.Lewis announced this morning that he will be leaving Southern(3108 Olive Street) after a brief transition period to open a new restaurant at 4270 Manchester Avenue, the spot in the Grove most recently inhabited by Sweetie Pie's and (briefly) Sweet Times at the Mangrove. His partner in the venture will be his partner in life, wife Elisa Lewis.…