For some the art of bondage and sadomasochism, or BDSM, is about giving up control, for others it is about taking it, and now two Hongkongers are teaching others how to explore their desires in a safe environment.Tommy Jai and Po Po G run a class in Tsim Sha Tsui that, in the conservative city of Hong Kong, is lifting the lid on one darker aspect of sex, and judging by the programme’s popularity, it is an element of adult relationships that some are keen to learn more about.The Fifty Shades…