Rename alert model to SystemFeedback

cms/static/js/models/alert.js

-CMS.Models.Alert = Backbone.Model.extend({
-    defaults: {
-        "type": null,
-        "title": null,
-        "message": null,
-        "shown": true
-    }
-});

cms/static/js/models/feedback.js

+CMS.Models.SystemFeedback = Backbone.Model.extend({
+    defaults: {
+        "type": null,  // "warning", "confirmation", "error", "announcement", "step-required"
+        "title": null,
+        "message": null,
+        "shown": true,
+        "close": false  // show a close button?
+        /* could also have an "actions" hash: here is an example demonstrating
+           the expected structure
+        "actions": {
+            "primary": {
+                "text": "Save",
+                "class": "action-save",
+                "click": function(model) {
+                    // do something when Save is clicked
+                }
+            },
+            "secondary": [
+                {
+                    "text": "Cancel",
+                    "class": "action-cancel",
+                    "click": function(model) {}
+                }, {
+                    "text": "Discard Changes",
+                    "class": "action-discard",
+                    "click": function(model) {}
+                }
+            ]
+        }
+        */
+    }
+});