[Import/Export] Adds Import and Export functionality

Added context actions for importing and exporting JSON representations of domain objects. Added FileInputService for triggering file picker and retrieving uploaded data. Also added a File Input form control for integration with MCTForms.

platform/forms/res/templates/controls/file-input.html

@@ -0,0 +1,30 @@
+<!--
+ Open MCT, Copyright (c) 2014-2017, United States Government
+ as represented by the Administrator of the National Aeronautics and Space
+ Administration. All rights reserved.
+
+ Open MCT 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 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.
+-->
+
+<a class="s-button {{structure.cssClass}}"
+   ng-model="ngModel[field]"
+   ng-class="{ labeled: structure.text }"
+   mct-file-input>
+    <span class="title-label" ng-if="structure.text">
+        {{structure.text}}
+    </span>
+</a>