Add ability to exit retail mode

Added ability to exit retail mode via factory reset. Only show the demo
user if the user is a demo user.

Test: Manual - exiting performs factory reset
Change-Id: Ic749a2ae69bcd5a7900c2b64c129ae3904348a64
Fixes: 71871702
Fixes: 71871695
Fixes: 71645485
Fixes: 71645479
diff --git a/AndroidManifest.xml b/AndroidManifest.xml
index 30feb98..6fcbd21 100644
--- a/AndroidManifest.xml
+++ b/AndroidManifest.xml
@@ -42,6 +42,7 @@
     <uses-permission android:name="android.permission.INTERNET"/>
     <uses-permission android:name="android.permission.MANAGE_ACCOUNTS"/>
     <uses-permission android:name="android.permission.MANAGE_USERS"/>
+    <uses-permission android:name="android.permission.MASTER_CLEAR" />
     <uses-permission android:name="android.permission.OVERRIDE_WIFI_CONFIG"/>
     <uses-permission android:name="android.permission.READ_CONTACTS"/>
     <uses-permission android:name="android.permission.REBOOT"/>