androidNameForApiLevel: Api-Level 20 is Android L

That's unlikely to be the final name, but introduce it for now.

Change-Id: Iaf1fd65e797a2354433b9bb5af6a6d76ecb8409c
Reviewed-by: Eskil Abrahamsen Blomfeldt <eskil.abrahamsen-blomfeldt@digia.com>

src/plugins/android/androidmanager.cpp

@@ -793,6 +793,8 @@ QString AndroidManager::androidNameForApiLevel(int x)
         return QLatin1String("Android 4.3");
     case 19:
         return QLatin1String("Android 4.4");
+    case 20:
+        return QLatin1String("Android L"); // prelimary name?
     default:
         return tr("Unknown Android version. API Level: %1").arg(QString::number(x));
     }