stacker: Add documentation, allow on emulator.

apps/stacker/README.md

@@ -5,7 +5,8 @@ A simple game of stacking cubes.
 
 ## Usage
 
-Press the button to stack!
+Boxes move horizontally. Use button to stack them on top of existing
+boxes. You win when you reach top of the screen.
 
 ## Creator
 

apps/stacker/metadata.json

@@ -6,6 +6,7 @@
   "icon": "app.png",
   "tags": "game",
   "supports" : ["BANGLEJS", "BANGLEJS2"],
+  "allow_emulator": true,
   "readme": "README.md",
   "storage": [
     {"name":"stacker.app.js","url":"app.js"},