[Core] Add missing models

When requested models are missing, add models of an explicitly
unknown type to allow this to be expressed to the user.
WTD-1241.

platform/core/bundle.json

@@ -70,6 +70,12 @@
                 "type": "decorator",
                 "implementation": "models/CachingModelDecorator.js"
             },
+            {
+                "provides": "modelService",
+                "type": "decorator",
+                "priority": "fallback",
+                "implementation": "models/MissingModelDecorator.js"
+            },
             {
                 "provides": "typeService",
                 "type": "provider",
@@ -132,6 +138,11 @@
                 "features": "creation",
                 "description": "A folder, useful for storing and organizing domain objects.",
                 "model": { "composition": [] }
+            },
+            {
+                "key": "unknown",
+                "name": "Unknown Type",
+                "glyph": "?"
             }
         ],
         "capabilities": [
@@ -193,4 +204,4 @@
             }
         ]
     }
-}
+}

platform/core/src/models/MissingModelDecorator.js

@@ -0,0 +1,54 @@
+/*****************************************************************************
+ * Open MCT Web, Copyright (c) 2014-2015, United States Government
+ * as represented by the Administrator of the National Aeronautics and Space
+ * Administration. All rights reserved.
+ *
+ * Open MCT Web is licensed under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ * http://www.apache.org/licenses/LICENSE-2.0.
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+ * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
+ * License for the specific language governing permissions and limitations
+ * under the License.
+ *
+ * Open MCT Web includes source code licensed under additional open source
+ * licenses. See the Open Source Licenses file (LICENSES.md) included with
+ * this source code distribution or the Licensing information page available
+ * at runtime from the About dialog for additional information.
+ *****************************************************************************/
+
+/*global define*/
+define(
+    [],
+    function () {
+        "use strict";
+
+        function MissingModelDecorator(modelService) {
+            function missingModel(id) {
+                return {
+                    type: "unknown",
+                    name: "Missing: " + id
+                };
+            }
+
+            return {
+                getModels: function (ids) {
+                    function addMissingModels(models) {
+                        var result = {};
+                        ids.forEach(function (id) {
+                            result[id] = models[id] || missingModel(id);
+                        });
+                        return result;
+                    }
+
+                    return modelService.getModels(ids).then(addMissingModels);
+                }
+            };
+        }
+
+        return MissingModelDecorator;
+    }
+);