Integration (with myself) fixes

- Adding default value in empty frames to avoid artifact when paint
bucketing (you may have issues with previously stored model before this
commit, no migration plan for papybrossette :D)
 - Fix issue: Model does not show up when loading a remote GAE model
 - Removing FRAMESHEET_UPDATED events (remains of history manager
implementation)

js/Constants.js

@@ -1,6 +1,16 @@
 var Constants = {
 
-	DEFAULT_PEN_COLOR : '#000000',
-	TRANSPARENT_COLOR : "TRANSPARENT",
+	DEFAULT_PEN_COLOR : '#000000',	
+	TRANSPARENT_COLOR : 'TRANSPARENT',
+	
+	/*
+	 * Fake semi-transparent color used to highlight transparent
+	 * strokes and rectangles:
+	 */
+	SELECTION_TRANSPARENT_COLOR: 'rgba(255, 255, 255, 0.6)',
+	
+	/*
+	 * Default entry point for piskel web service:
+	 */
 	PISKEL_SERVICE_URL: 'http://2.piskel-app.appspot.com'
 };