NorthStar Bank has tapped a veteran banker to test the commercial lending waters in St. Petersburg. The bank is opening a loan production office at 100 Second Ave. S downtown. Julie Stapf, who joined NorthStar in 2013 as vice president of commercial banking, will lead the new location. Stapf is a Pinellas County native who's been in the banking industry for more than 25 years. David Stone, NorthStar president and CEO, called St. Petersburg "a great market ... that frankly our bank is not known...