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/applications/ProcessStatsDetail.java

@@ -30,7 +30,6 @@ import android.net.Uri;
 import android.os.Bundle;
 import android.os.Process;
 import android.os.UserHandle;
-import android.preference.PreferenceActivity;
 import android.text.format.Formatter;
 import android.view.LayoutInflater;
 import android.view.View;
@@ -161,7 +160,6 @@ public class ProcessStatsDetail extends Fragment implements Button.OnClickListen
     }
 
     private void doAction(int action) {
-        PreferenceActivity pa = (PreferenceActivity)getActivity();
         switch (action) {
             case ACTION_FORCE_STOP:
                 killProcesses();