[ADF-506] Unify thumbnail service (#2014)

* move thumbnail service in core

* fix folder

ng2-components/ng2-alfresco-core/index.ts

@@ -47,7 +47,9 @@ import {
     LogServiceMock,
     NotificationService,
     ContentService,
-    AppConfigService, InitAppConfigServiceProvider
+    AppConfigService,
+    InitAppConfigServiceProvider,
+    ThumbnailService
 } from './src/services/index';
 
 import { FileSizePipe } from './src/pipes/file-size.pipe';
@@ -93,7 +95,8 @@ export function providers() {
         ContentService,
         AuthGuard,
         AuthGuardEcm,
-        AuthGuardBpm
+        AuthGuardBpm,
+        ThumbnailService
     ];
 }