title: ngx-translate .instant returns key instead of value
body: <p>I am trying to make a method which would accept string key and return translated string value by using translate.instant(parameter). The problem is that it returns key(parameter). Usually this is returned if it doesn't find translation. I think the problem is that method gets called before loader loads translations.</p>
  
  <p>My app.module.ts imports:</p>
  
  <pre><code>    TranslateModule.forRoot({
    loader: {
      provide: TranslateLoader,
      useFactory: (createTranslateLoader),
      deps: [HttpClient]
    }
  })
  </code></pre>
  
  <p>createTranslateLoader function: </p>
  
  <pre><code>    export function createTranslateLoader(http: HttpClient) {
    return new TranslateHttpLoader(http, './assets/i18n/', '.json');
  }
  </code></pre>
  
  <p>In my app.component:</p>
  
  <pre><code>constructor(public translate: TranslateService){
     translate.setDefaultLang('en');
     translate.use('en');
  }
  </code></pre>
  
  <p>When I translate in html using pipes it works ok.</p>