Call gulp and grunt programmatically instead of using child_process.exec()

[der-On]

To be able to use the "geddy" global in those generators.

[der-On]

Gulp changed it's API. On cannot use gulp.run() anymore. So I have to investigate if there are other ways to call gulp programatically.

[emarcha]

@der-On did you find any other way to call gulp programmatically?

[der-On]

@emarcha To be honest. I haven't touched this in years and am not using geddy anymore as it kind of "died".