Get the DNX version from global.json in build script so that it's only configured in one place.
Get the DNX version from global.json in build script so that it's only configured in one place.

onovotny/Autofac,autofac/Autofac,jango2015/Autofac,zjmpds/Autofac,zmaruo/Autofac,liujunhua/Autofac,laizhan/autofac,laizhan/autofac,liujunhua/Autofac,laizhan/autofac,lijianguang/Autofac,laizhan/autofac,onovotny/Autofac