demo(app): removed the library installed from npm and used the linked one

Author: AnthonyNahas

demo/package-lock.json

@@ -26,7 +26,6 @@
   },
   "private": true,
   "dependencies": {
-    "@angular-material-extensions/link-preview": "^1.0.2",
     "@angular/animations": "^7.1.4",
     "@angular/cdk": "^7.2.0",
     "@angular/common": "^7.1.4",

demo/package.json

@@ -4,6 +4,7 @@ import {HomeComponent} from './home.component';
 import {MatLinkPreviewModule} from '@angular-material-extensions/link-preview';
 import {MatCardModule, MatInputModule} from '@angular/material';
 import {MarkdownModule} from 'ngx-markdown';
+import {HttpClient, HttpClientModule} from '@angular/common/http';
 
 describe('HomeComponent', () => {
   let component: HomeComponent;