Fix win dll not loading

[henrivain]

Fixes bug: #8 Nuget package does not copy native libraries to build output on Windows

• Change csproj parameters to pack dll into nuget package.
• Change DllName to "tesseract53.dll" in TesseractApi.cs to point to output dir (Same with leptonica)
• Change windows dlls to be copied to output directory when building project (so works with new DllName)