Support Ansi coloring on AppVeyor

[devlead]

As discussed https://gitter.im/cake-build/cake?at=59eedb5f01110b7231f32461

AppVeyor supports ANSI color codes, probably possible to replace logger to support colors with Cake

[devlead]

Basically should be a matter of replacing IConsole ( https://github.com/cake-build/cake/blob/develop/src/Cake.Core/IConsole.cs )