By ANDREA MAGRATH Breaking free: Bieber negotiated with police to be allowed to go out on to his balcony to greet fans after he was warned he would 'incite a riot' Singer warned by police he could be charged with 'inciting a riot' if he steps outsideBieber negotiates balcony appearance with authoritiesFans cautioned by police amid scenes of pandemonium at Hard Days Night hotelLiverpool residents