Zen mode configuration panel. (packages/apps/Settings)

Read-only version of the configuration screen for
Limited Interruptions.  Defaults to the logic implemented
for this mode, namely block notifications except for
Calls & Alarms.

This settings panel will serve as a target for the
configure affordance in SystemUI.

Change-Id: I33fd1e11ab76dbb7044bb94cb096cd892945947d

src/com/android/settings/Settings.java

@@ -85,6 +85,7 @@ public class Settings extends SettingsActivity {
     public static class PaymentSettingsActivity extends SettingsActivity { /* empty */ }
     public static class PrintSettingsActivity extends SettingsActivity { /* empty */ }
     public static class PrintJobSettingsActivity extends SettingsActivity { /* empty */ }
+    public static class ZenModeSettingsActivity extends SettingsActivity { /* empty */ }
 
     public static class TopLevelSettings extends SettingsActivity { /* empty */ }
 }