BERLIN (Reuters) – Renowned British conductor Simon Rattle said on Thursday he would step down as head of the prestigious Berlin Philharmonic in 2018 when his current contract with the orchestra expires and before he turns 64. "In 2018 I will be nearly 64 years old," the 57-year-old said in a statement on the Philharmonic's website. "As a Liverpool boy, it is impossible not to think of the Beatles' question 'Will you still need me… when I'm 64?'" he joked. "This was not an easy decision. I love this orchestra and therefore wanted to tell them my decision as early as possible. …