Add PrimeNG

1. npm install

npm install --save primeng
npm install --save primeui
npm install --save font-awesome

2. Add external font-awesome

3. Add external scripts and styles

    {src: 'primeui/primeui-ng-all.min.css', inject: true},
    {src: 'primeui/primeui-ng-all.min.js', inject: true}

Do you need add font-awesome.min.css to, you can modify seed.confi.ts or proceed like above

/**
 * The list of local files to be injected in the `index.html`.
 * @type {InjectableDependency[]}
 */
APP_ASSETS: InjectableDependency[] = [
  { src: `${this.CSS_SRC}/main.${ this.getInjectableStyleExtension() }`, inject: true, vendor: false },
  { src: `${this.CSS_SRC}/font-awesome.min.css`, inject: true, vendor: true }
];