Along a busy highway on the outskirts of Vietnam’s largest city, a worn-out looking woman carrying all her worldly possessions in a handful of plastic bags picks her way through a web of swaying hammocks, looking for one that’s empty so she can lay her weary head down for the night.It’s about 10pm and she has already paid her 20,000 dong (86 US cents) entry fee, which includes use of the hammock cafe’s showers, plug sockets, Wi-fi, blankets and drinking water.As trucks rumble past on the…