Add nuspec and build script

Took the liberty and added a build script for tesseract. It would be awesome if you could
publish the package to nuget. It would literaly take you 1 minute todo it :dancers: 

```ps
.\Build.ps1 -packageversion 1.0.0
```

Produces a nupkg package with Tesseract 2.0, 3.5, 4.0, 4.5, 4.5.1 in bin\x86\Release folder ;)

You only have to upload it