Fix .NET 2 compilation

[1upbyte]

No crazy changes at all, just fixing compile errors. I am by no means a C# dev, so if I did something silly I apologize in advance, I just wanted to try out the pass the hash features and integrate them into my project Devious-WinRM and noticed it wasn't compiling. Will these changes be released / compiled for the public now that they compile? Love the project!