SelectDirectoryService.InitialDirectory property fixed.

after removing the initialization of the RootFolder, the InitialDirectory began to work
Please use something like this:

```
if (string.IsNullOrWhitespace(initialDirectory))
{
     browserDialog.SelectedPath = initialDirectory;
}
else
{
    browserDialog.RootFolder = System.Environment.SpecialFolder.MyComputer;
}
```