add addWidget and removeWidget functions

widget_add_remove_sample.lua

@@ -0,0 +1,11 @@
+function onResume()
+    ui:showButtons({ "Add clock widget", "Remove clock widget" })
+end
+
+function onClick(idx)
+    if idx == 1 then
+        aio:addWidget("clock")
+    else
+        aio:removeWidget("clock")
+    end
+end