Change to build to use dotnet

[victorhurdugaci]

At a minimum, you have to upgrade a few scripts and project.json files just like here: aspnet/Configuration@9cfd22f

[pranavkm]

Currently blocked on dotnet/cli#798
Curently blocked on https://github.com/dotnet/cli/issues/807
Currently blocked on https://github.com/dotnet/cli/issues/882
https://github.com/dotnet/cli/issues/987

[victorhurdugaci]

dotnet/cli#807 is fixed