Update webpack to 4.0.0

[flut1]

I updated everything to make the build and dev commands work without error. However, we should thoroughly review the new configuration before merging. Particularly:

• the mode: 'development' and mode: 'production' provide a lot of default config for us. This might allow us to remove some of our existing config.
• CommonsChunkPlugin has been replaced with the optimization config. I am now using the default configuration for that. We should verify if that is what we want. See https://gist.github.com/sokra/1522d586b8e5c0f5072d7565c2bee693
• Same as above for the uglify plugin. We also need to check if the default options suffice
• Added an alpha version of extract-text-webpack-plugin. We might want to wait for stable
• We should check if there are any new webpack options we want to take advantage of

[flut1]

There are some issues with awesome-typescript-loader that need to be resolved first. See s-panferov/awesome-typescript-loader#534

[ThaNarie]

This one is automatically on in development mode, so can be removed.

[ThaNarie]

Ah wait, this is prod, maybe we want to leave it on here :) (but can be removed from dev config)

NamedModulesPlugin -> optimization.namedModules (on by default in develoment mode)

[ThaNarie]

webpack.NoEmitOnErrorsPlugin can also be removed if i'm correct.

NoEmitOnErrorsPlugin -> optimization.noEmitOnErrors (on by default in production mode)

[ThaNarie]

Not sure if we want this, but:

Resolving can now be configured with module.rules[].resolve. It's merged with the global configuration.

So we could add .vue resolve in the vue loader config, so if you disable the loader rules, the resolving also will be removed. Best practices and all..

[ThaNarie]

ModuleConcatenationPlugin -> optimization.concatenateModules (on by default in production mode)

So we can remove this one as well

[flut1]

I implemented the suggestions by @ThaNarie above.
Updated awesome-typescript-loader to 5.0.0-0, which fixes most issues. However, there is still a problem with the "lib" option in tsconfig.json. I removed it for now, because we seem te be using the default anway

[flut1]

@hjeti I fixed the TS issues (see latest commit). As far as I know this can be safely merged. It might be good though for someone to test these changes more extensively (for example, apply them in an existing project)

[flut1]

Just tested it by applying the changes to an existing project. All worked fine (tested dev server and prod build).