LONDON (Reuters) - Pop star George Michael said smoking cannabis kept him "sane and happy" and appeared to light up a joint during an interview on ITV news channel, ITV said on Friday. The comments have landed the former Wham! frontman in hot water with mental health groups and drug charities concerned about the message Michael's comments will send to young people. "All drugs have potential to harm and that is the principal message we need to get across," William Butler, spokesman for the Addaction drugs charity, told the Evening Standard. A spokeswoman for the 43-year-old singer, who recently embarked...