Update system setting page subtext

- Move android version from about phone subtext to system update
- Updates strings for autofill, keyboard & input, factory reset, swipe
  for notification
- Add a new pref category for spell checker and personal dictionary
- Display "None" if any default app is not selected
- Display current keyboard type as language subtext

Bug: 36395109
Test: make RunSettingsRoboTests
Change-Id: Id6ca94ea31e55f1c1ec04e47dcf657a25c35c7fe

src/com/android/settings/applications/defaultapps/DefaultAppPreferenceController.java

@@ -24,6 +24,7 @@ import android.support.v7.preference.Preference;
 import android.text.TextUtils;
 import android.util.Log;
 
+import com.android.settings.R;
 import com.android.settings.applications.PackageManagerWrapper;
 import com.android.settings.applications.PackageManagerWrapperImpl;
 import com.android.settings.core.PreferenceController;
@@ -56,7 +57,7 @@ public abstract class DefaultAppPreferenceController extends PreferenceControlle
             preference.setSummary(defaultAppLabel);
         } else {
             Log.d(TAG, "No default app");
-            preference.setSummary(null);
+            preference.setSummary(R.string.app_list_preference_none);
         }
         mayUpdateGearIcon(app, preference);
     }