SDK: add Switch preference option

Change-Id: I2edacdc4d18ad801d023c4074045f01f72457f47

SDK/Templates/preferences.json

@@ -28,5 +28,13 @@
         "summary" : "preference summary",
         "defaultValue" : "default value",
         "scope" : "plugin, Name of API implementation"
+    },
+    {
+        "category" : "genericSwitch",
+        "type" : "Switch",
+        "key": "keyName",
+        "title" : "preference title",
+        "summary" : "preference summary",
+        "defaultValue" : "default value"
     }
 ]