Complete NuGet package support including a new rakefile.

You could have just pulled the nuspec out of the existing package, but that
wouldn't have been any fun. I present, instead, a starter Rake build. You can
build, test, and package the Release mode solution. I hope this is a good start
and leads to more automation!

You can easily install Ruby and a gem/package manager, Bundler, on Windows
using Chocolatey, the Windows application package manager (see
http://chocolatey.org).

    > cinst ruby
    > cgem bundler

Then, ask Bundler to install all of the required gems

    > bundle

Then, ask Rake about the tasks in the rakefile

    > rake -T

Or just run the "default" task

    > rake