Update template dependencies for webpack 3 (was: App template: Update to webpack 3)

[alex3683]

Currently the webpack-dev-server is still not webpack 2 aware. As soon as this is no longer an issue, we should update.
See webpack/webpack-dev-server#932

[jpommerening]

webpack/webpack-dev-server#946 (comment)

[x1B]

After giving it a quick spin against a LaxarJS2/Vue.js app, it definitely feels faster now. HMR also still working, so I guess this is go.

[alex3683]

Are we treating this as a breaking change? (See LaxarJS/laxar#470 (comment))

[x1B]

@alex3683 I think, for a change to the generator to be breaking, it would mean that a new version can no longer generate widgets/activities for an application created with an older version. So this would not be breaking.

[alex3683]

@x1B Okay, that is in accordance to what @jpommerening and me discussed yesterday.

[alex3683]

Changed the title, since more plugins and other dependencies needed to be lifted to be compatible with webpack 3.

[alex3683]

Implemented on master (v2.1.0).

Upgrade Information

Since webpack 3 was announced to be non-breaking, we assume that there will be no problems with this change. Our tests showed none.
By default the new ModuleConcatenationPlugin for Scope Hoisting is loaded. Feel free to remove it in the generated app, if you don't want it.