title: Get browser language on startup using Service
body: <p>I want to get browser language on application startup. For that I wrote service which looks like:</p>
  
  <pre><code>import { Injectable } from '@angular/core';
  import { TranslateService } from 'ng2-translate/ng2-translate';
  
  @Injectable()
  export class LanguageService {
  
  constructor(public translate: TranslateService) {
      let browserLang = translate.getBrowserLang();
      translate.use(browserLang.match(/en|ge/) ? browserLang : 'en');
  }
  }
  </code></pre>
  
  <p>and in app.module.ts I've added this service:</p>
  
  <pre><code>bootstrap: [ AppComponent, [ LanguageService ] ]
  </code></pre>
  
  <p>but when it executes in console appears this error:</p>
  
  <blockquote>
    <p>(index):18 Error: (SystemJS) No Directive annotation found on LanguageService(…)</p>
  </blockquote>
  
  <p>what's wrong?</p>