Feature [--migrate]: Validate the generated webpack 2 configuration.

[pksjce]

Do you want to request a feature or report a bug?
Feature

What is the current behavior?
The generated webpack 2 config needs to be validated with the webpack schema.

If this is a feature request, what is motivation or use case for changing the behavior?
This feature needs to be present for basic hygeine

[evenstensberg]

@pksjce Working with webpack schema at parser now, could give you feedback on what I'm thinking of it once I'm done.

[evenstensberg]

Resolved in #99