If you've always wished you could make like Inspector Gadget and go-go-Gadget springs, have we got news for you. Crunch Gym, purveyors of "judgment-free fitness," just introduced a new class at their Union Square location (113 4th Avenue at 12th St.) guaranteed to be a hoppin' good time. In BOING with Kangoo, participants strap on a ridiculous pair of Kangoo Jumps, fitness shoes that look like ...