title: regId is always empty
body: <p>I'm currenlty implementing GCM into my app. I used the tutorial <a href="https://developer.android.com/google/gcm/index.html" rel="nofollow">here</a> as a start point. </p>
  
  <p>The problem is that my <code>regId</code> is always <code>null</code>:</p>
  
  <pre><code>GCMRegistrar.checkDevice(this);
  GCMRegistrar.checkManifest(this);
  final String regId = GCMRegistrar.getRegistrationId(this);
  
  if (regId.equals(""))
  {
      GCMRegistrar.register(this, "627xxxx78");
  }
  else
  {
      if (GCMRegistrar.isRegisteredOnServer(this))
      {
          Log.i(TAG, "Already registered regId : " + regId );
      }
      else
      {
          final Context context = this;
  
          mRegisterTask = new AsyncTask&lt;Void, Void, Void&gt;() {
              @Override
              protected Void doInBackground(Void... params) {
                  boolean registered =
                          ServerUtilities.register(context, regId);
  
                  if (!registered)
                  {
                      GCMRegistrar.unregister(context);
                  }
                  return null;
              }
  
              @Override
              protected void onPostExecute(Void result) {
                  mRegisterTask = null;
              }
          };
  
          mRegisterTask.execute(null, null, null);
      }
  }
  </code></pre>
  
  <p>In the code above, <code>ServerUtilities.register</code> is never called because  <code>GCMRegistrar.getRegistrationId(this)</code>; always returns an empty string.</p>
  
  <p>Any ideas?</p>