WIP: Integrate IPython setup on windows

I tested this on a brand new windows system with nothing but julia installed:

````julia
Pkg.clone("https://github.com/davidanthoff/IJulia.jl.git","IJulia")
Pkg.checkout("IJulia", "integratedipysetup")
Pkg.build("IJulia")

using IJulia
notebook()
````

works on that system.

This PR lacks proper error handling etc, consider it more a proof of concept.
If the user already has IPython, e.g. they have Anaconda installed, shouldn't we use that rather than installing our own?