A Sudanese migrant has been jailed after brutally attacking a charity volunteer who was collecting rubbish near a migrant camp in northern France.The 40-year-old assaulted the worker from social support charity AUDASSE in an unprovoked attack while he was about to do a litter-picking round in Calais. AUDASSE works with vulnerable people, including helping direct them towards accommodation.The court heard that the defendant approached the open wi…