feat(data): show skeleton screens before data is loaded

Closes #4

src/app/_helpers/fake-backend.interceptor.ts

@@ -17,7 +17,7 @@ import {HTTP_INTERCEPTORS, HttpClient,
 import {Injectable} from '@angular/core';
 import {SCIndexResponse, SCThingType} from '@openstapps/core';
 import {Observable, of} from 'rxjs';
-import {map} from 'rxjs/operators';
+import {map, delay} from 'rxjs/operators';
 import {SampleThings} from './data/sample-things';
 
 const sampleIndexResponse: SCIndexResponse = {
@@ -150,12 +150,12 @@ export class FakeBackendInterceptor implements HttpInterceptor {
             return this.sampleFetcher.getSampleThing(request.body.filter.arguments.value)
                     .pipe(map((sampleData: any) => {
               return new HttpResponse({status: 200, body: {data: sampleData}});
-            }));
+            }), delay(1000)); // add delay for skeleton screens to be seen (see !16)
           }
         }
         return this.sampleFetcher.getSampleThings().pipe(map((sampleData: any) => {
           return new HttpResponse({status: 200, body: {data: sampleData}});
-        }));
+        }), delay(1000)); // add delay for skeleton screens to be seen (see !16)
       }
     }
     return next.handle(request);