Tests for atime and mtime
Tests for atime and mtime

- should not modify file mtime and atime when not provided on the vinyl stat
- should write file mtime using the vinyl mtime
- should write file atime and mtime using the vinyl stat

vineethawal/vinyl-fs,hgwood/vinyl-fs,Klowner/vinyl-fs,doowb/vinyl-fs,tmcgee123/vinyl-fs,ckross01/vinyl-fs,rlugojr/vinyl-fs