Associated Press: In the foothills of the Swiss Alps four new steel-gray towers rise from what used to be a grassy field. One of them is home to Transocean Ltd., the world’s biggest offshore drilling contractor and owner of the Deepwater Horizon rig that exploded in the Gulf of Mexico, leading to one of the worst oil spills in history. Low taxes prompted the decision two years ago to move to landlocked Switzerland: The company paid 16 percent tax on its $4.4 billion global operating income last year. …