Use Drawer in Settings app

- get rid of PreferenceActivity as much as we can and use fragments instead
- add Drawer widget
- add Dashboard high level entry into the Drawer (but this is work in progress and would be done in another CL)
- add bypass of fragment's Header  validation when launched from the Drawer but *force* validation if external
call thru an Intent

Be aware that WifiPickerActivity should remain for now a PreferenceActivity. It is used by SetupWizard and should
not trigger running the SettingsActivity's header building code. SetupWizard is a Home during the provisionnig process
and then deactivate itself as a Home but would make the Home header to appear in the Drawer (because momentarily we
would have two Home).

Also, verified that:

- the WiFi settings still work when called from SetupWizard
- when you have multiple Launchers, the Home header will appear in the list of Headers in the Drawer

Change-Id: I407a5e0fdd843ad7615d3d511c416a44e3d97c90

src/com/android/settings/accounts/SyncSettingsActivity.java

@@ -16,22 +16,20 @@
 
 package com.android.settings.accounts;
 
-import android.app.Fragment;
 import android.content.Intent;
-import android.preference.PreferenceActivity;
 
-import com.android.settings.ChooseLockGeneric.ChooseLockGenericFragment;
+import com.android.settings.SettingsActivity;
 
 /**
  * Launcher activity for the SyncSettings fragment.
  *
  */
-public class SyncSettingsActivity extends PreferenceActivity {
+public class SyncSettingsActivity extends SettingsActivity {
     @Override
     public Intent getIntent() {
-        Intent modIntent = new Intent(super.getIntent());
-        modIntent.putExtra(EXTRA_SHOW_FRAGMENT, SyncSettings.class.getName());
-        modIntent.putExtra(EXTRA_NO_HEADERS, true);
+        Intent modIntent = new Intent(getIntent());
+        modIntent.putExtra(SettingsActivity.EXTRA_SHOW_FRAGMENT, SyncSettings.class.getName());
+        modIntent.putExtra(SettingsActivity.EXTRA_NO_HEADERS, true);
         return modIntent;
     }