Does not parse VS2013 solution files

[SonnevilleJ]

Awesome project; I have a use for this and was happy to find this project. However, this issue is a blocker for me:

Executing the following code returns an Onion.SolutionParser.Parser.Model.Solution object with null Global and Projects fields. No exception is thrown to indicate any parsing failure.

SolutionParser.Parse(path)

Where path is the filename of a .sln file in Visual Studio 2013 format.