Dip-dyed hair? Forget it. For headbangin’ locks that want to look all kinds of cool, it’s got to be streaky stripes. First spotted on the SS14 catwalks (big-ups to you, Ashish), colourful (and wash-out) chalky stripes on tresses are the freshest way to make your festival hair as epic as your outfit. Get in on the easy-peasy know-how…