smartcardManager: add way to detect if user logged using (any) token

If a user uses a token at login time, we need to make sure they continue
to use the token at unlock time.

As a prerequisite for addressing that problem we need to know up front
if a user logged in with a token at all.

This commit adds the necessary api to detect that case.

js/misc/smartcardManager.js

@@ -112,6 +112,13 @@ var SmartcardManager = new Lang.Class({
             return false;
 
         return true;
+    },
+
+    loggedInWithToken() {
+        if (this._loginToken)
+            return true;
+
+        return false;
     }
 
 });