update CHANGELOG for v3.1.5
update CHANGELOG for v3.1.5

kewaunited/money,antstorm/money,RubyMoney/money,pixeltrix/money,paulodiniz/money,bonusly/money,gregoryhappyfresh/money,BrandyMint/money,insphire/money,maicoin/money,envato/money,richardvenneman/money,bnmrrs/money,printercu/money,saizai/money,AlexVPopov/money,nilbus/money