Solved Issue #260 in a better way

Solves in a better way the bug "SingleProcessFileAppender crashes on startup".
 I didn't have the tools and I'm a newby in GitHub therefore I think the online editor has made some more changes in the tabs (or spaces) before the code. 

Basically, it has been changed the constructor and the GetFileInfo method following the same pattern like in the CountingSingleProcessFileAppender