On a night of flashy and expensive store parties, Betsey Johnson went the renegade route and threw a street party in front of her shuttered boutique on 138 Wooster St. on Thursday night during Fashion’s Night Out. Johnson, whose 90 namesake stores shuttered this spring after they went bankrupt, announced via Twitter that she would hold a party on the street. Six hundred fans gathered outside the boutique Thursday evening to party with Johnson, along with a few friendly cops, who took pictures with the designer. Signs outside the boutique read, “The stores were closed, but Betsey lives.” Johnson, whose business is now owned by Steve Madden, will present her spring 2013 collection Tuesday.