Make dpm command output more test friendly

Added 'Success' at the beginning of the command output every time
it didn't fail, so that we can easily check the output in tests.
The command is brand new, only used by us on CTS tests, so this
shouldn't break anybody.

Bug: 17312478
Change-Id: Ie67bf5b2f44e658e7009e5bd87f8cb81be515584

cmds/dpm/src/com/android/commands/dpm/Dpm.java

@@ -94,7 +94,7 @@ public final class Dpm extends BaseCommand {
             mDevicePolicyManager.removeActiveAdmin(component, UserHandle.USER_OWNER);
             throw e;
         }
-        System.out.println("Device owner set to package " + packageName);
+        System.out.println("Success: Device owner set to package " + packageName);
         System.out.println("Active admin set to component " + component.toShortString());
     }
 
@@ -113,8 +113,8 @@ public final class Dpm extends BaseCommand {
             mDevicePolicyManager.removeActiveAdmin(component, userId);
             throw e;
         }
-        System.out.println("Active admin and profile owner set to " + component.toShortString() +
-                " for user " + userId);
+        System.out.println("Success: Active admin and profile owner set to "
+                + component.toShortString() + " for user " + userId);
     }
 
     private ComponentName parseComponentName(String component) {