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/sidenav/sidenav.component.ts

@@ -23,7 +23,7 @@
  * along with Alfresco. If not, see <http://www.gnu.org/licenses/>.
  */
 
-import { Subject } from 'rxjs/Rx';
+import { Subject } from 'rxjs';
 import { Component, Input, OnInit, OnDestroy } from '@angular/core';
 import { ExtensionService } from '../../extensions/extension.service';
 import { Store } from '@ngrx/store';