This is required, because there may be plugins that use the
tns-core-modules builder.

fixes #561

implements #569 

BREAKING CHANGES:

The dependencies that were previously added by the nativescript-dev-webpack plugin to the project's package.json are now dependencies of the plugin itself.

MIGRATION:
1. Remove all obsolete dependencies from your project. You can do that by invoking the script:
```
./node_modules/.bin/update-ns-webpack --deps
```
2. [Angular] Add the following packages as devDependencies:
```
//package.json

"devDependencies": {
    "@angular-devkit/build-angular": "~0.7.0-rc.0",
    "@angular/compiler-cli": "~6.1.0-beta.1",
    //...
}
```