Fix fs.copyFileSync not supported in Node 6
Fix fs.copyFileSync not supported in Node 6

microsoft/TypeScript,Microsoft/TypeScript,minestarks/TypeScript,basarat/TypeScript,alexeagle/TypeScript,alexeagle/TypeScript,RyanCavanaugh/TypeScript,microsoft/TypeScript,basarat/TypeScript,kitsonk/TypeScript,kpreisser/TypeScript,nojvek/TypeScript,SaschaNaz/TypeScript,SaschaNaz/TypeScript,donaldpipowitch/TypeScript,minestarks/TypeScript,nojvek/TypeScript,kitsonk/TypeScript,Microsoft/TypeScript,Microsoft/TypeScript,minestarks/TypeScript,nojvek/TypeScript,alexeagle/TypeScript,weswigham/TypeScript,RyanCavanaugh/TypeScript,microsoft/TypeScript,SaschaNaz/TypeScript,basarat/TypeScript,kpreisser/TypeScript,basarat/TypeScript,donaldpipowitch/TypeScript,nojvek/TypeScript,kitsonk/TypeScript,weswigham/TypeScript,kpreisser/TypeScript,weswigham/TypeScript,SaschaNaz/TypeScript,donaldpipowitch/TypeScript,donaldpipowitch/TypeScript,RyanCavanaugh/TypeScript