LONDON (Reuters) - Britain's media regulator gave pay-TV firm BSkyB a clean bill of health on Thursday, saying there was no evidence it was linked to a phone hacking scandal which engulfed Rupert Murdoch's News Corp, its largest shareholder. The ruling by Ofcom, which has clashed repeatedly with BSkyB in the past, will lift a cloud that had long hung over the hugely successful group and will allow it to focus on the challenges of intensifying competition and growing economic pressures on its customers. ...