User Manager service to manage users and query user details

Moved a bunch of methods from PackageManager to UserManager.

Fix launching of activities from recents to correct user.

Guest creation APIs

Change-Id: I0733405e6eb2829675665e225c759d6baa2b708f
diff --git a/services/java/com/android/server/SystemServer.java b/services/java/com/android/server/SystemServer.java
index 96cf3d3..e8350c1 100644
--- a/services/java/com/android/server/SystemServer.java
+++ b/services/java/com/android/server/SystemServer.java
@@ -55,6 +55,7 @@
 import com.android.server.net.NetworkPolicyManagerService;
 import com.android.server.net.NetworkStatsService;
 import com.android.server.pm.PackageManagerService;
+import com.android.server.pm.UserManagerService;
 import com.android.server.power.PowerManagerService;
 import com.android.server.power.ShutdownThread;
 import com.android.server.usb.UsbService;
@@ -192,6 +193,11 @@
             }
 
             ActivityManagerService.setSystemProcess();
+            
+            Slog.i(TAG, "User Service");
+            ServiceManager.addService(Context.USER_SERVICE,
+                    UserManagerService.getInstance(context));
+
 
             mContentResolver = context.getContentResolver();