Remove more entries not relevant to wifi-only devices.

Bug: 3488384
Bug: 3487976
Bug: 3488381

Removed Cell standby entry from Battery use screen.
Removed Mobile signal strength from BatteryHistory screen.
Added wifi IP address to About->Status
Remove auto-timezone checkbox in Settings->Date & time

Change-Id: I228721a3613b1aeb600026e42274337886552698

src/com/android/settings/DateTimeSettings.java

@@ -87,6 +87,12 @@ public class DateTimeSettings extends SettingsPreferenceFragment
         mAutoTimePref = (CheckBoxPreference) findPreference(KEY_AUTO_TIME);
         mAutoTimePref.setChecked(autoTimeEnabled);
         mAutoTimeZonePref = (CheckBoxPreference) findPreference(KEY_AUTO_TIME_ZONE);
+        // Override auto-timezone if it's a wifi-only device.
+        // TODO: Remove this when auto-timezone is implemented based on wifi-location.
+        if (Utils.isWifiOnly()) {
+            getPreferenceScreen().removePreference(mAutoTimeZonePref);
+            autoTimeZoneEnabled = false;
+        }
         mAutoTimeZonePref.setChecked(autoTimeZoneEnabled);
 
         mTimePref = findPreference("time");
@@ -125,7 +131,6 @@ public class DateTimeSettings extends SettingsPreferenceFragment
         mTimeZone.setEnabled(!autoTimeZoneEnabled);
     }
 
-
     @Override
     public void onResume() {
         super.onResume();