Msftidy: check comma at end (ruby 1.8 compatibility)

This commit adds a check to msftidy to detect commas at the end of definitions since this breaks ruby 1.8 compatibility

example
```ruby
'Payload' =>
{
  'Space'    => 1024,
  'BadChars' => "\x00",
  'MinNops'  => 512, <--
}
```