Switch to @pauldotknopf's VroomJs branch

[Daniel15]

@pauldotknopf's branch: https://github.com/pauldotknopf/vroomjs-core

This is required for the ASP.NET Core version, as ASP.NET Core projects require all dependencies to be NuGet packages and I'd rather use a version of VroomJs that's already packaged rather than rolling my own package.

Need to wait until pauldotknopf/vroomjs-core#6 is merged
Need to test on Linux and ensure it still works