Want to hold your next party at a dentist’s office? How about a flower shop, an art gallery or a furniture store? All these spaces and more — think ice cream parlors, churches and even nail salons — have found willing renters via Peerspace, a San Francisco startup that offers short-term rentals of spaces for meetings and events. The appeal of the Airbnb-style concept is obvious for hotels, restaurants, bars and other traditional venues.