Dev eromano external viewer (#1636)

* add extensibility point to add a custom viewer

* documentation and tests

* add example in document list

ng2-components/ng2-alfresco-viewer/src/components/imgViewer.component.ts

@@ -0,0 +1,39 @@
+/*!
+ * @license
+ * Copyright 2016 Alfresco Software, Ltd.
+ *
+ * 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.
+ */
+
+import { Component, Input } from '@angular/core';
+
+@Component({
+    moduleId: module.id,
+    selector: 'img-viewer',
+    templateUrl: './imgViewer.component.html',
+    styleUrls: ['./imgViewer.component.css']
+})
+export class ImgViewerComponent {
+
+    @Input()
+    urlFile: string;
+
+    @Input()
+    nameFile: string;
+
+    ngOnChanges(changes) {
+        if (!this.urlFile) {
+            throw new Error('Attribute urlFile is required');
+        }
+    }
+}