Generic Assert methods for NUnit, plus repo cleanup

Hi Daniel,

I'm sending along my implementation of an Assert class with generic methods for use with NUnit. The methods work just like the methods provided by `NUnit.Framework.Assert`, but they use F# generics to constrain the types of the arguments passed to them; this helps avoid making simple mistakes which can arise due to F#'s type inference when writing unit tests.

On an unrelated note, I noticed there were a ton of unnecessary binaries stored in the repository, so I deleted nearly all of them and added a .gitignore to avoid the situation in future. The solution now uses NuGet package restore to grab the NUnit, xUnit, NHamcrest, and other libraries it needs automatically. The solution and projects build successfully, though you should double-check your build/deploy scripts to make sure they're still able to find everything they need.

Regards,
Jack