Fix latency from beep to "Listening" state. Bug 2326485.

Remove the initial beep from the voice dialer app. This makes it
more consistent with Voice Search and eliminates the latency
issue on certain devices where it can take hundreds of milliseconds
after the beep before audio input is ready.
diff --git a/src/com/android/voicedialer/VoiceDialerActivity.java b/src/com/android/voicedialer/VoiceDialerActivity.java
index 36c99f9..380d7b7 100644
--- a/src/com/android/voicedialer/VoiceDialerActivity.java
+++ b/src/com/android/voicedialer/VoiceDialerActivity.java
@@ -154,19 +154,10 @@
     };
 
     private void startWork() {
-        // prompt the user with a beep
-        final int msec = playSound(ToneGenerator.TONE_PROP_PROMPT);
-
-        // start the engine after the beep
+        // start the engine
         mRecognizerThread = new Thread() {
             public void run() {
                 if (Config.LOGD) Log.d(TAG, "onCreate.Runnable.run");
-                try {
-                    Thread.sleep(msec);
-                } catch (InterruptedException e) {
-                    return;
-                }
-                if (mToneGenerator != null) mToneGenerator.stopTone();
                 mEngine.recognize(VoiceDialerActivity.this,
                         newFile(getArg(MICROPHONE_EXTRA)),
                         newFile(getArg(CONTACTS_EXTRA)),