title: how to work with dynamic argument (urls) in Observable.forkJoin()
body: <p>SO I love forkJoin, basically the replacement of Promise.all, but I can't figure how to feed it a dynamic list as in:</p>
  
  <pre><code>Observable.forkJoin(
          this.http.get('/app/books.json').map((res:Response) =&gt; res.json()),
          this.http.get('/app/movies.json').map((res:Response) =&gt; res.json())
      ).subscribe(
        data =&gt; {
          this.books = data[0]
          this.movies = data[1]
        },
        err =&gt; console.error(err)
      );
  </code></pre>
  
  <p>only that I need to create the http.gets at runtime (the URLs will be different, destinations and total URLs generated all will be dynamic), tried to pass a config object but it didn't like it...</p>
  
  <p>tx for reading,</p>
  
  <p>Sean.</p>