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/Utils.java

@@ -42,7 +42,6 @@ import android.os.Bundle;
 import android.os.UserHandle;
 import android.os.UserManager;
 import android.preference.Preference;
-import android.preference.PreferenceActivity.Header;
 import android.preference.PreferenceFrameLayout;
 import android.preference.PreferenceGroup;
 import android.provider.ContactsContract.CommonDataKinds;
@@ -238,7 +237,7 @@ public class Utils {
     }
 
     public static boolean updateHeaderToSpecificActivityFromMetaDataOrRemove(Context context,
-            List<Header> target, Header header) {
+            List<SettingsActivity.Header> target, SettingsActivity.Header header) {
 
         Intent intent = header.intent;
         if (intent != null) {