RCL-ify the package

[rickbutterfield]

As per the opinionated package starter, convert the package to be a Razor Class Library as per some of the discussions on the PR:

So to explain why RCLs are awesome, I think one of the key takeways is that when you're working locally in Visual Studio or similar, the assets from the package is added to your project virtually. Meaning that aren't physically on disk inside your project - they are instead pulled virtually from the NuGet package and made to appear as if they were inside your project. For one, this makes it easier to work in packages and version control, since you don't have to commit the assets to your repo.