Fixes an exception that occurs on startup in apps using NLog. AFAIK shou...

Fixes a problem I'm having with the current version from nuget when I try to run my app. 
I tried to write tests but couldn't get test assembly to compile with current VS solution & projects for 4.5. Seems to be some conflict on whether it's using xunit or nunit? 
Anyway, this seems to be the right fix. If not help me understand what I'm missing and I'll try to make it better!