Adding NuGet package specification files and .gitignore

Dear Martin,

This is Mauricio from ITS.
I have creates a NuGet package specification file for this project. Now TUIO v1.1 can be included into C# projects directly from Visual Studio. Just need to install the NuGet package manager. Instructions can be found here: https://www.nuget.org/packages/libTUIO11/.

Thank you!