WIP: Add DocPlagiarizer NuGet package

The documentation comment copying build task (that's quite a mouthful) is now on NuGet. So removed the old dll's and project nodes and added it through NuGet instead.

Yeah, DocPlagiarizer is what it's called now. Because naming projects should be done by someone else.
Just have the WIP on this so that I can look over it once more on here.

Closes #388