A more informative error message

I was losing my mind trying to figure out why the file wasn't found or accessible. This was my config file

    {
      indent: 4
    }

And with this change you get:

    Error opening config file C:\User....
    [SyntaxError: Unexpected token i]

Which was what allowed me to figure out that JSON syntax was the problem.
Merge pull request #87 from ubershmekel/patch-1

A more informative error message