If Al-Shabaab was behind the terrorist attack in Nairobi, then the group has come a long way since its foundation in a derelict shampoo factory called Ifka Halane — ‘Clean and Shiny’ — in Mogadishu in 2006. I know a little about the group because I am the only westerner to have met its founder, Aden Hashi Ayro, before he was killed in a US air strike.