No include plugins defined in base to dev, dist and test

[dzwiedziu-nkg]

Generated webpack config no include plugins from base.js to dev.js and dist.js. Moreover no include plugins and resolve.alias to test.js.

My proposals:

1. Add config.plugins = baseConfig.plugins.concat(config.plugins); line before module.exports = config; in cfg/dev.js and cfg/dist.js like in my commit in my project.
2. Add module.exports.resolve.alias = Object.assign({}, baseConfig.resolve.alias, module.exports.resolve.alias); and module.exports.plugins = baseConfig.plugins.concat(module.exports.plugins); lines at the end of cfg/test.js like in my commit.