Added input sanitization for backup path
Added input sanitization for backup path

- We need to limit the allowed filename accepted by the method to avoid opening up path traversal attack

bitjson/Ghost,TryGhost/Ghost,kevinansfield/Ghost,ErisDS/Ghost,JohnONolan/Ghost,JohnONolan/Ghost,kevinansfield/Ghost,JohnONolan/Ghost,TryGhost/Ghost,ErisDS/Ghost,e10/Ghost,janvt/Ghost,ErisDS/Ghost,bitjson/Ghost,kevinansfield/Ghost,janvt/Ghost,TryGhost/Ghost,e10/Ghost