By Tatiana Krisztina The missing 16-year-old child of two Silicon Valley tech tycoons has been found alive in the back of a white van a week after vanishing in a crime-riddled neighbourhood. Mint Butterfield’s parents are Slack co-founder Stewart Butterfield, who is estimated to be worth $1.6billion, and Flickr tycoon Caterina Fake, who is worth $25million. We’ll be bringing you the very latest updates, pictures and video on this breaking news story. Please check back regularly for updates on this developing story HERE . Get email updates on the day’s biggest stories straight to your inbox by …