Imagine you’re in London. So far, so good, right? Now imagine you’re at a Bruce Springsteen show in London. Pretty cool. And then imagine that during the big finale, Bruce Springsteen invites some guy named Paul McCartney onstage to play a few more, if you can even imagine that much. And then, while The Boss, Sir McCartney, and the E Street Band are playing “Twist and Shout,” the concert organizers (i.e. “The Man”) suddenly cut the power out because 10:30 was getting a little late for their liking. Now stop imagining that before your head falls off from hypothetical outrage, but that is exactly what happened to 80,000 concert goers at Hyde Park last Saturday. Admittedly, there was some sort of 10pm curfew but then, rock-and-roll knows no curfew. Or, as the E Street Band’s Steven Van Zandt tweeted, “When I’m jamming with McCartney, don’t bug me!” …