Small refactor of mime-guessing PR
Small refactor of mime-guessing PR

sohelrana820/flysystem,mapyo/flysystem,dstockto/flysystem,Amrit01/flysystem,twistor/flysystem,oswaldderiemaecker/flysystem,dshafik/flysystem,twistor/flysystem,barryvdh/flysystem,mhlavac/flysystem,hannesvdvreken/flysystem,CarsonF/flysystem,sachintaware/flysystem,rossriley/flysystem,farmisen/flysystem,mhlavac/flysystem,nao-pon/flysystem,concrete5/flysystem