content api service (#455)

* introduce content-api service

* upgrade files component

* upgrade directives

* upgrade directives

* update directives

* fix profile resolver call ordering issue

* fix reducer

* update services

* extra apis

* update about page

* update preview component

* code updates

src/app/components/shared-files/shared-files.component.ts

@@ -51,6 +51,7 @@ export class SharedFilesComponent extends PageComponent implements OnInit {
             this.content.nodesDeleted.subscribe(() => this.reload()),
             this.content.nodesMoved.subscribe(() => this.reload()),
             this.content.nodesRestored.subscribe(() => this.reload()),
+            this.content.linksUnshared.subscribe(() => this.reload()),
             this.uploadService.fileUploadError.subscribe((error) => this.onFileUploadedError(error))
         ]);
     }