App & channel notification settings updates

- change 'block all' to an on/off switch bar
- update channel list summary text when notifications are
toggled on/off on app settings page
- Add 'off state' text
- change style of foot items
- change 'importance' from a dropdown to its own page

Bug: 37538972
Bug: 37479730
Fixes: 37541624
Fixes: 37549732
Test: manual

Change-Id: I0e5cc66ba539ce2b76b4ad6541bf6bfb5b58c373

src/com/android/settings/notification/NotificationSoundPreference.java

@@ -1,3 +1,19 @@
+/*
+ * Copyright (C) 2017 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
 package com.android.settings.notification;
 
 import android.content.ContentResolver;