In the rudderless, post-Internet music world, it takes more than a few catchy songs to get noticed. Fledgling acts can try to craft viral videos (such as OK Go) or perhaps embrace anonymity (such as The Weeknd) to garner buzz. When they emerged last summer, West London soul act Jungle tried both, and — judging by the exuberance of the packed house at the Black Cat on Tuesday — it worked.