TezCommonUtils should ensure that permissions are properly granted

I found TezClientUtils has method ensureStagingDirExists.It will check whether the path "stagingArea" exists, if it exists, check the permission, if not, call the function "TezCommonUtils.mkDirForAM" to create.But in method mkDirForAM,it use mkdir(path, permission) to create, if umask too strict such as 777,this directory will set with 000 permission.So we need to ensure the directory has right permission.