Angular 6 (#556)

* upgrade to angular 6 (with rxjs-compat)

* fix tests

* fix test scripts

* upgrade rxjs to 6.0

* remove rxjs-compat layer

* update unit tests

* restore tests

* context-menu transparent backdrop

* upgrade libs

* changed snackbar locator

* locator as class

* remove locator element reference

* snackbar locators

* wait for snackbar before executing the action button

* expect cdk-overlay before mat-menu-panel condition

* update libs

src/app/components/page.component.ts

@@ -28,12 +28,11 @@ import { OnDestroy, OnInit, ViewChild } from '@angular/core';
 import { Store } from '@ngrx/store';
 import { MinimalNodeEntity, MinimalNodeEntryEntity } from 'alfresco-js-api';
 import { takeUntil } from 'rxjs/operators';
-import { Subject, Subscription } from 'rxjs/Rx';
+import { Subject, Subscription ,  Observable } from 'rxjs';
 import { SetSelectedNodesAction, ViewFileAction } from '../store/actions';
 import { appSelection, sharedUrl, currentFolder, infoDrawerOpened, documentDisplayMode } from '../store/selectors/app.selectors';
 import { AppStore } from '../store/states/app.state';
 import { SelectionState } from '../store/states/selection.state';
-import { Observable } from 'rxjs/Rx';
 import { ExtensionService } from '../extensions/extension.service';
 import { ContentManagementService } from '../services/content-management.service';
 import { ContentActionRef } from '../extensions/action.extensions';