Adding csproj to the react-flux-babel-karma #87

Heya,

Someone asked me a while ago to add a csproj to this project so if they want to use Visual Studio as their editor they can without fiddling with setup themselves. Apparently the advice currently in place is slightly problematic. I'm up for doing the work but I thought I'd check first if you were likely to take the PR?

I'd probably use this as a basis for plugging Visual Studio into the mix:

https://github.com/johnnyreilly/poorclaresarundel/tree/master/PoorClaresAngular

I'm using this approach demonstrated in this repo commercially so I'm fairly happy it's battle tested.

But as I say, your call if you want it.